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• Harvard Referencing for Journal Articles | Templates & Examples

Harvard Referencing for Journal Articles | Templates & Examples

Published on 20 May 2020 by Jack Caulfield . Revised on 7 November 2022.

In Harvard style, to reference a journal article, you need the author name(s), the year, the article title, the journal name, the volume and issue numbers, and the page range on which the article appears.

If you accessed the article online, add a DOI (digital object identifier) if available.

Scribbr’s free Harvard reference generator can instantly create accurate references for a wide variety of source types:

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Table of contents

Online-only journal articles, articles with multiple authors, referencing a whole issue of a journal, referencing a preprint journal article, frequently asked questions about referencing journal articles in harvard style.

To reference an online journal article with no print version, always include the DOI if available. No access date is necessary with a DOI. Note that a page range may not be available for online-only articles; in this case, simply leave it out, as in this example.

Online-only article with no DOI

When you need to reference an online-only article which doesn’t have a DOI, use a URL instead – preferably the stable URL often listed with the article. In this case, you do need to include an access date.

Note that if an online article has no DOI but does have a print equivalent, you don’t need to include a URL. The details of the print journal should be enough for the reader to locate the article.

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Journal articles often have multiple authors. In both your in-text citations and reference list, list up to three authors in full. Use the first author’s name followed by ‘ et al. ’ when there are four or more.

When you want to reference an entire issue of a journal instead of an individual article, you list the issue editor(s) in the author position and give the title of the issue (if available) rather than of an individual article.

When you reference an article that’s been accepted for publication but not yet published, the format changes to acknowledge this.

If it’s unknown where or whether the article will be published, omit this information:

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In Harvard referencing, up to three author names are included in an in-text citation or reference list entry. When there are four or more authors, include only the first, followed by ‘ et al. ’

In Harvard style , when you quote directly from a source that includes page numbers, your in-text citation must include a page number. For example: (Smith, 2014, p. 33).

You can also include page numbers to point the reader towards a passage that you paraphrased . If you refer to the general ideas or findings of the source as a whole, you don’t need to include a page number.

Cite this Scribbr article

If you want to cite this source, you can copy and paste the citation or click the ‘Cite this Scribbr article’ button to automatically add the citation to our free Reference Generator.

Caulfield, J. (2022, November 07). Harvard Referencing for Journal Articles | Templates & Examples. Scribbr. Retrieved 20 May 2024, from https://www.scribbr.co.uk/referencing/harvard-journal-article-reference/

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Reference List: Common Reference List Examples

Article (with doi).

Alvarez, E., & Tippins, S. (2019). Socialization agents that Puerto Rican college students use to make financial decisions. Journal of Social Change , 11 (1), 75–85. https://doi.org/10.5590/JOSC.2019.11.1.07

Laplante, J. P., & Nolin, C. (2014). Consultas and socially responsible investing in Guatemala: A case study examining Maya perspectives on the Indigenous right to free, prior, and informed consent. Society & Natural Resources , 27 , 231–248. https://doi.org/10.1080/08941920.2013.861554

Use the DOI number for the source whenever one is available. DOI stands for "digital object identifier," a number specific to the article that can help others locate the source. In APA 7, format the DOI as a web address. Active hyperlinks for DOIs and URLs should be used for documents meant for screen reading. Present these hyperlinks in blue and underlined text (the default formatting in Microsoft Word), although plain black text is also acceptable. Be consistent in your formatting choice for DOIs and URLs throughout your reference list. Also see our Quick Answer FAQ, "Can I use the DOI format provided by library databases?"

Jerrentrup, A., Mueller, T., Glowalla, U., Herder, M., Henrichs, N., Neubauer, A., & Schaefer, J. R. (2018). Teaching medicine with the help of “Dr. House.” PLoS ONE , 13 (3), Article e0193972. https://doi.org/10.1371/journal.pone.0193972

For journal articles that are assigned article numbers rather than page ranges, include the article number in place of the page range.

For more on citing electronic resources, see  Electronic Sources References .

Article (Without DOI)

Found in a common academic research database or in print.

Casler , T. (2020). Improving the graduate nursing experience through support on a social media platform. MEDSURG Nursing , 29 (2), 83–87.

If an article does not have a DOI and you retrieved it from a common academic research database through the university library, there is no need to include any additional electronic retrieval information. The reference list entry looks like the entry for a print copy of the article. (This format differs from APA 6 guidelines that recommended including the URL of a journal's homepage when the DOI was not available.) Note that APA 7 has additional guidance on reference list entries for articles found only in specific databases or archives such as Cochrane Database of Systematic Reviews, UpToDate, ProQuest Dissertations and Theses Global, and university archives. See APA 7, Section 9.30 for more information.

Found on an Open Access Website

Eaton, T. V., & Akers, M. D. (2007). Whistleblowing and good governance. CPA Journal , 77 (6), 66–71. http://archives.cpajournal.com/2007/607/essentials/p58.htm

Provide the direct web address/URL to a journal article found on the open web, often on an open access journal's website. In APA 7, active hyperlinks for DOIs and URLs should be used for documents meant for screen reading. Present these hyperlinks in blue and underlined text (the default formatting in Microsoft Word), although plain black text is also acceptable. Be consistent in your formatting choice for DOIs and URLs throughout your reference list.

Weinstein, J. A. (2010).  Social change  (3rd ed.). Rowman & Littlefield.

If the book has an edition number, include it in parentheses after the title of the book. If the book does not list any edition information, do not include an edition number. The edition number is not italicized.

American Nurses Association. (2015). Nursing: Scope and standards of practice (3rd ed.).

If the author and publisher are the same, only include the author in its regular place and omit the publisher.

Lencioni, P. (2012). The advantage: Why organizational health trumps everything else in business . Jossey-Bass. https://amzn.to/343XPSJ

As a change from APA 6 to APA 7, it is no longer necessary to include the ebook format in the title. However, if you listened to an audiobook and the content differs from the text version (e.g., abridged content) or your discussion highlights elements of the audiobook (e.g., narrator's performance), then note that it is an audiobook in the title element in brackets. For ebooks and online audiobooks, also include the DOI number (if available) or nondatabase URL but leave out the electronic retrieval element if the ebook was found in a common academic research database, as with journal articles. APA 7 allows for the shortening of long DOIs and URLs, as shown in this example. See APA 7, Section 9.36 for more information.

Chapter in an Edited Book

Poe, M. (2017). Reframing race in teaching writing across the curriculum. In F. Condon & V. A. Young (Eds.), Performing antiracist pedagogy in rhetoric, writing, and communication (pp. 87–105). University Press of Colorado.

Include the page numbers of the chapter in parentheses after the book title.

Christensen, L. (2001). For my people: Celebrating community through poetry. In B. Bigelow, B. Harvey, S. Karp, & L. Miller (Eds.), Rethinking our classrooms: Teaching for equity and justice (Vol. 2, pp. 16–17). Rethinking Schools.

Also include the volume number or edition number in the parenthetical information after the book title when relevant.

Freud, S. (1961). The ego and the id. In J. Strachey (Ed.),  The standard edition of the complete psychological works of Sigmund Freud  (Vol. 19, pp. 3-66). Hogarth Press. (Original work published 1923)

When a text has been republished as part of an anthology collection, after the author’s name include the date of the version that was read. At the end of the entry, place the date of the original publication inside parenthesis along with the note “original work published.” For in-text citations of republished work, use both dates in the parenthetical citation, original date first with a slash separating the years, as in this example: Freud (1923/1961). For more information on reprinted or republished works, see APA 7, Sections 9.40-9.41.

Classroom Resources

Citing classroom resources.

If you need to cite content found in your online classroom, use the author (if there is one listed), the year of publication (if available), the title of the document, and the main URL of Walden classrooms. For example, you are citing study notes titled "Health Effects of Exposure to Forest Fires," but you do not know the author's name, your reference entry will look like this:

Health effects of exposure to forest fires [Lecture notes]. (2005). Walden University Canvas. https://waldenu.instructure.com

If you do know the author of the document, your reference will look like this:

Smith, A. (2005). Health effects of exposure to forest fires [PowerPoint slides]. Walden University Canvas. https://waldenu.instructure.com  

A few notes on citing course materials:

• [Lecture notes]
• [Course handout]
• [Study notes]
• It can be difficult to determine authorship of classroom documents. If an author is listed on the document, use that. If the resource is clearly a product of Walden (such as the course-based videos), use Walden University as the author. If you are unsure or if no author is indicated, place the title in the author spot, as above.
• If you cannot determine a date of publication, you can use n.d. (for "no date") in place of the year.

Note:  The web location for Walden course materials is not directly retrievable without a password, and therefore, following APA guidelines, use the main URL for the class sites: https://class.waldenu.edu.

Citing Tempo Classroom Resources

Clear author: 

Smith, A. (2005). Health effects of exposure to forest fires [PowerPoint slides]. Walden University Brightspace. https://mytempo.waldenu.edu

Unclear author:

Health effects of exposure to forest fires [Lecture notes]. (2005). Walden University Brightspace. https://mytempo.waldenu.edu

Conference Sessions and Presentations

Feinman, Y. (2018, July 27). Alternative to proctoring in introductory statistics community college courses [Poster presentation]. Walden University Research Symposium, Minneapolis, MN, United States. https://scholarworks.waldenu.edu/symposium2018/23/

Torgerson, K., Parrill, J., & Haas, A. (2019, April 5-9). Tutoring strategies for online students [Conference session]. The Higher Learning Commission Annual Conference, Chicago, IL, United States. http://onlinewritingcenters.org/scholarship/torgerson-parrill-haas-2019/

Dictionary Entry

Merriam-Webster. (n.d.). Leadership. In Merriam-Webster.com dictionary . Retrieved May 28, 2020, from https://www.merriam-webster.com/dictionary/leadership

When constructing a reference for an entry in a dictionary or other reference work that has no byline (i.e., no named individual authors), use the name of the group—the institution, company, or organization—as author (e.g., Merriam Webster, American Psychological Association, etc.). The name of the entry goes in the title position, followed by "In" and the italicized name of the reference work (e.g., Merriam-Webster.com dictionary , APA dictionary of psychology ). In this instance, APA 7 recommends including a retrieval date as well for this online source since the contents of the page change over time. End the reference entry with the specific URL for the defined word.

Discussion Board Post

Osborne, C. S. (2010, June 29). Re: Environmental responsibility [Discussion post]. Walden University Canvas.  https://waldenu.instructure.com  

Dissertations or Theses

Retrieved From a Database

Nalumango, K. (2019). Perceptions about the asylum-seeking process in the United States after 9/11 (Publication No. 13879844) [Doctoral dissertation, Walden University]. ProQuest Dissertations and Theses.

Retrieved From an Institutional or Personal Website

Evener. J. (2018). Organizational learning in libraries at for-profit colleges and universities [Doctoral dissertation, Walden University]. ScholarWorks. https://scholarworks.waldenu.edu/cgi/viewcontent.cgi?article=6606&context=dissertations

Unpublished Dissertation or Thesis

Kirwan, J. G. (2005). An experimental study of the effects of small-group, face-to-face facilitated dialogues on the development of self-actualization levels: A movement towards fully functional persons [Unpublished doctoral dissertation]. Saybrook Graduate School and Research Center.

For further examples and information, see APA 7, Section 10.6.

Legal Material

For legal references, APA follows the recommendations of The Bluebook: A Uniform System of Citation , so if you have any questions beyond the examples provided in APA, seek out that resource as well.

Court Decisions

Reference format:

Name v. Name, Volume Reporter Page (Court Date). URL

Sample reference entry:

Brown v. Board of Education, 347 U.S. 483 (1954). https://www.oyez.org/cases/1940-1955/347us483

Sample citation:

In Brown v. Board of Education (1954), the Supreme Court ruled racial segregation in schools unconstitutional.

Note: Italicize the case name when it appears in the text of your paper.

Name of Act, Title Source § Section Number (Year). URL

Sample reference entry for a federal statute:

Individuals With Disabilities Education Act, 20 U.S.C. § 1400 et seq. (2004). https://www.congress.gov/108/plaws/publ446/PLAW-108publ446.pdf

Sample reference entry for a state statute:

Minnesota Nurse Practice Act, Minn. Stat. §§ 148.171 et seq. (2019). https://www.revisor.mn.gov/statutes/cite/148.171

Sample citation: Minnesota nurses must maintain current registration in order to practice (Minnesota Nurse Practice Act, 2010).

Note: The § symbol stands for "section." Use §§ for sections (plural). To find this symbol in Microsoft Word, go to "Insert" and click on Symbol." Look in the Latin 1-Supplement subset. Note: U.S.C. stands for "United States Code." Note: The Latin abbreviation " et seq. " means "and what follows" and is used when the act includes the cited section and ones that follow. Note: List the chapter first followed by the section or range of sections.

Unenacted Bills and Resolutions

(Those that did not pass and become law)

Title [if there is one], bill or resolution number, xxx Cong. (year). URL

Sample reference entry for Senate bill:

Anti-Phishing Act, S. 472, 109th Cong. (2005). https://www.congress.gov/bill/109th-congress/senate-bill/472

Sample reference entry for House of Representatives resolution:

Anti-Phishing Act, H.R. 1099, 109th Cong. (2005). https://www.congress.gov/bill/109th-congress/house-bill/1099

The Anti-Phishing Act (2005) proposed up to 5 years prison time for people running Internet scams.

These are the three legal areas you may be most apt to cite in your scholarly work. For more examples and explanation, see APA 7, Chapter 11.

Magazine Article

Clay, R. (2008, June). Science vs. ideology: Psychologists fight back about the misuse of research. Monitor on Psychology , 39 (6). https://www.apa.org/monitor/2008/06/ideology

Note that for citations, include only the year: Clay (2008). For magazine articles retrieved from a common academic research database, leave out the URL. For magazine articles from an online news website that is not an online version of a print magazine, follow the format for a webpage reference list entry.

Newspaper Article (Retrieved Online)

Baker, A. (2014, May 7). Connecticut students show gains in national tests. New York Times . http://www.nytimes.com/2014/05/08/nyregion/national-assessment-of-educational-progress-results-in-Connecticut-and-New-Jersey.html

Include the full date in the format Year, Month Day. Do not include a retrieval date for periodical sources found on websites. Note that for citations, include only the year: Baker (2014). For newspaper articles retrieved from a common academic research database, leave out the URL. For newspaper articles from an online news website that is not an online version of a print newspaper, follow the format for a webpage reference list entry.

OASIS Resources

Oasis webpage.

OASIS. (n.d.). Common reference list examples . Walden University. https://academicguides.waldenu.edu/writingcenter/apa/references/examples

For all OASIS content, list OASIS as the author. Because OASIS webpages do not include publication dates, use “n.d.” for the year.

Interactive Guide

OASIS. (n.d.). Embrace iterative research and writing [Interactive guide]. Walden University. https://academics.waldenu.edu/oasis/iterative-research-writing-web

For OASIS multimedia resources, such as interactive guides, include a description of the resource in brackets after the title.

Online Video/Webcast

Walden University. (2013).  An overview of learning  [Video]. Walden University Canvas.  https://waldenu.instructure.com  

Use this format for online videos such as Walden videos in classrooms. Most of our classroom videos are produced by Walden University, which will be listed as the author in your reference and citation. Note: Some examples of audiovisual materials in the APA manual show the word “Producer” in parentheses after the producer/author area. In consultation with the editors of the APA manual, we have determined that parenthetical is not necessary for the videos in our courses. The manual itself is unclear on the matter, however, so either approach should be accepted. Note that the speaker in the video does not appear in the reference list entry, but you may want to mention that person in your text. For instance, if you are viewing a video where Tobias Ball is the speaker, you might write the following: Tobias Ball stated that APA guidelines ensure a consistent presentation of information in student papers (Walden University, 2013). For more information on citing the speaker in a video, see our page on Common Citation Errors .

Taylor, R. [taylorphd07]. (2014, February 27). Scales of measurement [Video]. YouTube. https://www.youtube.com/watch?v=PDsMUlexaMY

OASIS. (2020, April 15). One-way ANCOVA: Introduction [Video]. YouTube. https://youtu.be/_XnNDQ5CNW8

For videos from streaming sites, use the person or organization who uploaded the video in the author space to ensure retrievability, whether or not that person is the speaker in the video. A username can be provided in square brackets. As a change from APA 6 to APA 7, include the publisher after the title, and do not use "Retrieved from" before the URL. See APA 7, Section 10.12 for more information and examples.

See also reference list entry formats for TED Talks .

Technical and Research Reports

Edwards, C. (2015). Lighting levels for isolated intersections: Leading to safety improvements (Report No. MnDOT 2015-05). Center for Transportation Studies. http://www.cts.umn.edu/Publications/ResearchReports/reportdetail.html?id=2402

Technical and research reports by governmental agencies and other research institutions usually follow a different publication process than scholarly, peer-reviewed journals. However, they present original research and are often useful for research papers. Sometimes, researchers refer to these types of reports as gray literature , and white papers are a type of this literature. See APA 7, Section 10.4 for more information.

Reference list entires for TED Talks follow the usual guidelines for multimedia content found online. There are two common places to find TED talks online, with slightly different reference list entry formats for each.

TED Talk on the TED website

If you find the TED Talk on the TED website, follow the format for an online video on an organizational website:

Owusu-Kesse, K. (2020, June). 5 needs that any COVID-19 response should meet [Video]. TED Conferences. https://www.ted.com/talks/kwame_owusu_kesse_5_needs_that_any_covid_19_response_should_meet

The speaker is the author in the reference list entry if the video is posted on the TED website. For citations, use the speaker's surname.

TED Talk on YouTube

If you find the TED Talk on YouTube or another streaming video website, follow the usual format for streaming video sites:

TED. (2021, February 5). The shadow pandemic of domestic violence during COVID-19 | Kemi DaSilvalbru [Video]. YouTube. https://www.youtube.com/watch?v=PGdID_ICFII

TED is the author in the reference list entry if the video is posted on YouTube since it is the channel on which the video is posted. For citations, use TED as the author.

Walden University Course Catalog

To include the Walden course catalog in your reference list, use this format:

Walden University. (2020). 2019-2020 Walden University catalog . https://catalog.waldenu.edu/index.php

If you cite from a specific portion of the catalog in your paper, indicate the appropriate section and paragraph number in your text:

...which reflects the commitment to social change expressed in Walden University's mission statement (Walden University, 2020, Vision, Mission, and Goals section, para. 2).

And in the reference list:

Walden University. (2020). Vision, mission, and goals. In 2019-2020 Walden University catalog. https://catalog.waldenu.edu/content.php?catoid=172&navoid=59420&hl=vision&returnto=search

Vartan, S. (2018, January 30). Why vacations matter for your health . CNN. https://www.cnn.com/travel/article/why-vacations-matter/index.html

For webpages on the open web, include the author, date, webpage title, organization/site name, and URL. (There is a slight variation for online versions of print newspapers or magazines. For those sources, follow the models in the previous sections of this page.)

American Federation of Teachers. (n.d.). Community schools . http://www.aft.org/issues/schoolreform/commschools/index.cfm

If there is no specified author, then use the organization’s name as the author. In such a case, there is no need to repeat the organization's name after the title.

In APA 7, active hyperlinks for DOIs and URLs should be used for documents meant for screen reading. Present these hyperlinks in blue and underlined text (the default formatting in Microsoft Word), although plain black text is also acceptable. Be consistent in your formatting choice for DOIs and URLs throughout your reference list.

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Knowledge Check: Common Reference List Examples

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Home » References in Research – Types, Examples and Writing Guide

References in Research – Types, Examples and Writing Guide

Table of Contents

References in Research

Definition:

References in research are a list of sources that a researcher has consulted or cited while conducting their study. They are an essential component of any academic work, including research papers, theses, dissertations, and other scholarly publications.

Types of References

There are several types of references used in research, and the type of reference depends on the source of information being cited. The most common types of references include:

References to books typically include the author’s name, title of the book, publisher, publication date, and place of publication.

Example: Smith, J. (2018). The Art of Writing. Penguin Books.

Journal Articles

References to journal articles usually include the author’s name, title of the article, name of the journal, volume and issue number, page numbers, and publication date.

Example: Johnson, T. (2021). The Impact of Social Media on Mental Health. Journal of Psychology, 32(4), 87-94.

Web sources

References to web sources should include the author or organization responsible for the content, the title of the page, the URL, and the date accessed.

Example: World Health Organization. (2020). Coronavirus disease (COVID-19) advice for the public. Retrieved from https://www.who.int/emergencies/disease/novel-coronavirus-2019/advice-for-public

Conference Proceedings

References to conference proceedings should include the author’s name, title of the paper, name of the conference, location of the conference, date of the conference, and page numbers.

Example: Chen, S., & Li, J. (2019). The Future of AI in Education. Proceedings of the International Conference on Educational Technology, Beijing, China, July 15-17, pp. 67-78.

References to reports typically include the author or organization responsible for the report, title of the report, publication date, and publisher.

Example: United Nations. (2020). The Sustainable Development Goals Report. United Nations.

Formats of References

Some common Formates of References with their examples are as follows:

APA (American Psychological Association) Style

The APA (American Psychological Association) Style has specific guidelines for formatting references used in academic papers, articles, and books. Here are the different reference formats in APA style with examples:

Author, A. A. (Year of publication). Title of book. Publisher.

Example : Smith, J. K. (2005). The psychology of social interaction. Wiley-Blackwell.

Journal Article

Author, A. A., Author, B. B., & Author, C. C. (Year of publication). Title of article. Title of Journal, volume number(issue number), page numbers.

Example : Brown, L. M., Keating, J. G., & Jones, S. M. (2012). The role of social support in coping with stress among African American adolescents. Journal of Research on Adolescence, 22(1), 218-233.

Author, A. A. (Year of publication or last update). Title of page. Website name. URL.

Example : Centers for Disease Control and Prevention. (2020, December 11). COVID-19: How to protect yourself and others. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html

Magazine article

Author, A. A. (Year, Month Day of publication). Title of article. Title of Magazine, volume number(issue number), page numbers.

Example : Smith, M. (2019, March 11). The power of positive thinking. Psychology Today, 52(3), 60-65.

Newspaper article:

Author, A. A. (Year, Month Day of publication). Title of article. Title of Newspaper, page numbers.

Example: Johnson, B. (2021, February 15). New study shows benefits of exercise on mental health. The New York Times, A8.

Edited book

Editor, E. E. (Ed.). (Year of publication). Title of book. Publisher.

Example : Thompson, J. P. (Ed.). (2014). Social work in the 21st century. Sage Publications.

Chapter in an edited book:

Author, A. A. (Year of publication). Title of chapter. In E. E. Editor (Ed.), Title of book (pp. page numbers). Publisher.

Example : Johnson, K. S. (2018). The future of social work: Challenges and opportunities. In J. P. Thompson (Ed.), Social work in the 21st century (pp. 105-118). Sage Publications.

MLA (Modern Language Association) Style

The MLA (Modern Language Association) Style is a widely used style for writing academic papers and essays in the humanities. Here are the different reference formats in MLA style:

Author’s Last name, First name. Title of Book. Publisher, Publication year.

Example : Smith, John. The Psychology of Social Interaction. Wiley-Blackwell, 2005.

Journal article

Author’s Last name, First name. “Title of Article.” Title of Journal, volume number, issue number, Publication year, page numbers.

Example : Brown, Laura M., et al. “The Role of Social Support in Coping with Stress among African American Adolescents.” Journal of Research on Adolescence, vol. 22, no. 1, 2012, pp. 218-233.

Author’s Last name, First name. “Title of Webpage.” Website Name, Publication date, URL.

Example : Centers for Disease Control and Prevention. “COVID-19: How to Protect Yourself and Others.” CDC, 11 Dec. 2020, https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.

Author’s Last name, First name. “Title of Article.” Title of Magazine, Publication date, page numbers.

Example : Smith, Mary. “The Power of Positive Thinking.” Psychology Today, Mar. 2019, pp. 60-65.

Newspaper article

Author’s Last name, First name. “Title of Article.” Title of Newspaper, Publication date, page numbers.

Example : Johnson, Bob. “New Study Shows Benefits of Exercise on Mental Health.” The New York Times, 15 Feb. 2021, p. A8.

Editor’s Last name, First name, editor. Title of Book. Publisher, Publication year.

Example : Thompson, John P., editor. Social Work in the 21st Century. Sage Publications, 2014.

Chapter in an edited book

Author’s Last name, First name. “Title of Chapter.” Title of Book, edited by Editor’s First Name Last name, Publisher, Publication year, page numbers.

Example : Johnson, Karen S. “The Future of Social Work: Challenges and Opportunities.” Social Work in the 21st Century, edited by John P. Thompson, Sage Publications, 2014, pp. 105-118.

Chicago Manual of Style

The Chicago Manual of Style is a widely used style for writing academic papers, dissertations, and books in the humanities and social sciences. Here are the different reference formats in Chicago style:

Example : Smith, John K. The Psychology of Social Interaction. Wiley-Blackwell, 2005.

Author’s Last name, First name. “Title of Article.” Title of Journal volume number, no. issue number (Publication year): page numbers.

Example : Brown, Laura M., John G. Keating, and Sarah M. Jones. “The Role of Social Support in Coping with Stress among African American Adolescents.” Journal of Research on Adolescence 22, no. 1 (2012): 218-233.

Author’s Last name, First name. “Title of Webpage.” Website Name. Publication date. URL.

Example : Centers for Disease Control and Prevention. “COVID-19: How to Protect Yourself and Others.” CDC. December 11, 2020. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.

Author’s Last name, First name. “Title of Article.” Title of Magazine, Publication date.

Example : Smith, Mary. “The Power of Positive Thinking.” Psychology Today, March 2019.

Author’s Last name, First name. “Title of Article.” Title of Newspaper, Publication date.

Example : Johnson, Bob. “New Study Shows Benefits of Exercise on Mental Health.” The New York Times, February 15, 2021.

Example : Thompson, John P., ed. Social Work in the 21st Century. Sage Publications, 2014.

Author’s Last name, First name. “Title of Chapter.” In Title of Book, edited by Editor’s First Name Last Name, page numbers. Publisher, Publication year.

Example : Johnson, Karen S. “The Future of Social Work: Challenges and Opportunities.” In Social Work in the 21st Century, edited by John P. Thompson, 105-118. Sage Publications, 2014.

Harvard Style

The Harvard Style, also known as the Author-Date System, is a widely used style for writing academic papers and essays in the social sciences. Here are the different reference formats in Harvard Style:

Author’s Last name, First name. Year of publication. Title of Book. Place of publication: Publisher.

Example : Smith, John. 2005. The Psychology of Social Interaction. Oxford: Wiley-Blackwell.

Author’s Last name, First name. Year of publication. “Title of Article.” Title of Journal volume number (issue number): page numbers.

Example: Brown, Laura M., John G. Keating, and Sarah M. Jones. 2012. “The Role of Social Support in Coping with Stress among African American Adolescents.” Journal of Research on Adolescence 22 (1): 218-233.

Author’s Last name, First name. Year of publication. “Title of Webpage.” Website Name. URL. Accessed date.

Example : Centers for Disease Control and Prevention. 2020. “COVID-19: How to Protect Yourself and Others.” CDC. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html. Accessed April 1, 2023.

Author’s Last name, First name. Year of publication. “Title of Article.” Title of Magazine, month and date of publication.

Example : Smith, Mary. 2019. “The Power of Positive Thinking.” Psychology Today, March 2019.

Author’s Last name, First name. Year of publication. “Title of Article.” Title of Newspaper, month and date of publication.

Example : Johnson, Bob. 2021. “New Study Shows Benefits of Exercise on Mental Health.” The New York Times, February 15, 2021.

Editor’s Last name, First name, ed. Year of publication. Title of Book. Place of publication: Publisher.

Example : Thompson, John P., ed. 2014. Social Work in the 21st Century. Thousand Oaks, CA: Sage Publications.

Author’s Last name, First name. Year of publication. “Title of Chapter.” In Title of Book, edited by Editor’s First Name Last Name, page numbers. Place of publication: Publisher.

Example : Johnson, Karen S. 2014. “The Future of Social Work: Challenges and Opportunities.” In Social Work in the 21st Century, edited by John P. Thompson, 105-118. Thousand Oaks, CA: Sage Publications.

Vancouver Style

The Vancouver Style, also known as the Uniform Requirements for Manuscripts Submitted to Biomedical Journals, is a widely used style for writing academic papers in the biomedical sciences. Here are the different reference formats in Vancouver Style:

Author’s Last name, First name. Title of Book. Edition number. Place of publication: Publisher; Year of publication.

Example : Smith, John K. The Psychology of Social Interaction. 2nd ed. Oxford: Wiley-Blackwell; 2005.

Author’s Last name, First name. Title of Article. Abbreviated Journal Title. Year of publication; volume number(issue number):page numbers.

Example : Brown LM, Keating JG, Jones SM. The Role of Social Support in Coping with Stress among African American Adolescents. J Res Adolesc. 2012;22(1):218-233.

Author’s Last name, First name. Title of Webpage. Website Name [Internet]. Publication date. [cited date]. Available from: URL.

Example : Centers for Disease Control and Prevention. COVID-19: How to Protect Yourself and Others [Internet]. 2020 Dec 11. [cited 2023 Apr 1]. Available from: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.

Author’s Last name, First name. Title of Article. Title of Magazine. Year of publication; month and day of publication:page numbers.

Example : Smith M. The Power of Positive Thinking. Psychology Today. 2019 Mar 1:32-35.

Author’s Last name, First name. Title of Article. Title of Newspaper. Year of publication; month and day of publication:page numbers.

Example : Johnson B. New Study Shows Benefits of Exercise on Mental Health. The New York Times. 2021 Feb 15:A4.

Editor’s Last name, First name, editor. Title of Book. Edition number. Place of publication: Publisher; Year of publication.

Example: Thompson JP, editor. Social Work in the 21st Century. 1st ed. Thousand Oaks, CA: Sage Publications; 2014.

Author’s Last name, First name. Title of Chapter. In: Editor’s Last name, First name, editor. Title of Book. Edition number. Place of publication: Publisher; Year of publication. page numbers.

Example : Johnson KS. The Future of Social Work: Challenges and Opportunities. In: Thompson JP, editor. Social Work in the 21st Century. 1st ed. Thousand Oaks, CA: Sage Publications; 2014. p. 105-118.

Turabian Style

Turabian style is a variation of the Chicago style used in academic writing, particularly in the fields of history and humanities. Here are the different reference formats in Turabian style:

Author’s Last name, First name. Title of Book. Place of publication: Publisher, Year of publication.

Example : Smith, John K. The Psychology of Social Interaction. Oxford: Wiley-Blackwell, 2005.

Author’s Last name, First name. “Title of Article.” Title of Journal volume number, no. issue number (Year of publication): page numbers.

Example : Brown, LM, Keating, JG, Jones, SM. “The Role of Social Support in Coping with Stress among African American Adolescents.” J Res Adolesc 22, no. 1 (2012): 218-233.

Author’s Last name, First name. “Title of Webpage.” Name of Website. Publication date. Accessed date. URL.

Example : Centers for Disease Control and Prevention. “COVID-19: How to Protect Yourself and Others.” CDC. December 11, 2020. Accessed April 1, 2023. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.

Author’s Last name, First name. “Title of Article.” Title of Magazine, Month Day, Year of publication, page numbers.

Example : Smith, M. “The Power of Positive Thinking.” Psychology Today, March 1, 2019, 32-35.

Author’s Last name, First name. “Title of Article.” Title of Newspaper, Month Day, Year of publication.

Example : Johnson, B. “New Study Shows Benefits of Exercise on Mental Health.” The New York Times, February 15, 2021.

Editor’s Last name, First name, ed. Title of Book. Place of publication: Publisher, Year of publication.

Example : Thompson, JP, ed. Social Work in the 21st Century. Thousand Oaks, CA: Sage Publications, 2014.

Author’s Last name, First name. “Title of Chapter.” In Title of Book, edited by Editor’s Last name, First name, page numbers. Place of publication: Publisher, Year of publication.

Example : Johnson, KS. “The Future of Social Work: Challenges and Opportunities.” In Social Work in the 21st Century, edited by Thompson, JP, 105-118. Thousand Oaks, CA: Sage Publications, 2014.

IEEE (Institute of Electrical and Electronics Engineers) Style

IEEE (Institute of Electrical and Electronics Engineers) style is commonly used in engineering, computer science, and other technical fields. Here are the different reference formats in IEEE style:

Author’s Last name, First name. Book Title. Place of Publication: Publisher, Year of publication.

Example : Oppenheim, A. V., & Schafer, R. W. Discrete-Time Signal Processing. Upper Saddle River, NJ: Prentice Hall, 2010.

Author’s Last name, First name. “Title of Article.” Abbreviated Journal Title, vol. number, no. issue number, pp. page numbers, Month year of publication.

Example: Shannon, C. E. “A Mathematical Theory of Communication.” Bell System Technical Journal, vol. 27, no. 3, pp. 379-423, July 1948.

Conference paper

Author’s Last name, First name. “Title of Paper.” In Title of Conference Proceedings, Place of Conference, Date of Conference, pp. page numbers, Year of publication.

Example: Gupta, S., & Kumar, P. “An Improved System of Linear Discriminant Analysis for Face Recognition.” In Proceedings of the 2011 International Conference on Computer Science and Network Technology, Harbin, China, Dec. 2011, pp. 144-147.

Author’s Last name, First name. “Title of Webpage.” Name of Website. Date of publication or last update. Accessed date. URL.

Example : National Aeronautics and Space Administration. “Apollo 11.” NASA. July 20, 1969. Accessed April 1, 2023. https://www.nasa.gov/mission_pages/apollo/apollo11.html.

Technical report

Author’s Last name, First name. “Title of Report.” Name of Institution or Organization, Report number, Year of publication.

Example : Smith, J. R. “Development of a New Solar Panel Technology.” National Renewable Energy Laboratory, NREL/TP-6A20-51645, 2011.

Author’s Last name, First name. “Title of Patent.” Patent number, Issue date.

Example : Suzuki, H. “Method of Producing Carbon Nanotubes.” US Patent 7,151,019, December 19, 2006.

Standard Title. Standard number, Publication date.

Example : IEEE Standard for Floating-Point Arithmetic. IEEE Std 754-2008, August 29, 2008

ACS (American Chemical Society) Style

ACS (American Chemical Society) style is commonly used in chemistry and related fields. Here are the different reference formats in ACS style:

Author’s Last name, First name; Author’s Last name, First name. Title of Article. Abbreviated Journal Title Year, Volume, Page Numbers.

Example : Wang, Y.; Zhao, X.; Cui, Y.; Ma, Y. Facile Preparation of Fe3O4/graphene Composites Using a Hydrothermal Method for High-Performance Lithium Ion Batteries. ACS Appl. Mater. Interfaces 2012, 4, 2715-2721.

Author’s Last name, First name. Book Title; Publisher: Place of Publication, Year of Publication.

Example : Carey, F. A. Organic Chemistry; McGraw-Hill: New York, 2008.

Author’s Last name, First name. Chapter Title. In Book Title; Editor’s Last name, First name, Ed.; Publisher: Place of Publication, Year of Publication; Volume number, Chapter number, Page Numbers.

Example : Grossman, R. B. Analytical Chemistry of Aerosols. In Aerosol Measurement: Principles, Techniques, and Applications; Baron, P. A.; Willeke, K., Eds.; Wiley-Interscience: New York, 2001; Chapter 10, pp 395-424.

Author’s Last name, First name. Title of Webpage. Website Name, URL (accessed date).

Example : National Institute of Standards and Technology. Atomic Spectra Database. https://www.nist.gov/pml/atomic-spectra-database (accessed April 1, 2023).

Author’s Last name, First name. Patent Number. Patent Date.

Example : Liu, Y.; Huang, H.; Chen, H.; Zhang, W. US Patent 9,999,999, December 31, 2022.

Author’s Last name, First name; Author’s Last name, First name. Title of Article. In Title of Conference Proceedings, Publisher: Place of Publication, Year of Publication; Volume Number, Page Numbers.

Example : Jia, H.; Xu, S.; Wu, Y.; Wu, Z.; Tang, Y.; Huang, X. Fast Adsorption of Organic Pollutants by Graphene Oxide. In Proceedings of the 15th International Conference on Environmental Science and Technology, American Chemical Society: Washington, DC, 2017; Volume 1, pp 223-228.

AMA (American Medical Association) Style

AMA (American Medical Association) style is commonly used in medical and scientific fields. Here are the different reference formats in AMA style:

Author’s Last name, First name. Article Title. Journal Abbreviation. Year; Volume(Issue):Page Numbers.

Example : Jones, R. A.; Smith, B. C. The Role of Vitamin D in Maintaining Bone Health. JAMA. 2019;321(17):1765-1773.

Author’s Last name, First name. Book Title. Edition number. Place of Publication: Publisher; Year.

Example : Guyton, A. C.; Hall, J. E. Textbook of Medical Physiology. 13th ed. Philadelphia, PA: Saunders; 2015.

Author’s Last name, First name. Chapter Title. In: Editor’s Last name, First name, ed. Book Title. Edition number. Place of Publication: Publisher; Year: Page Numbers.

Example: Rajakumar, K. Vitamin D and Bone Health. In: Holick, M. F., ed. Vitamin D: Physiology, Molecular Biology, and Clinical Applications. 2nd ed. New York, NY: Springer; 2010:211-222.

Author’s Last name, First name. Webpage Title. Website Name. URL. Published date. Updated date. Accessed date.

Example : National Cancer Institute. Breast Cancer Prevention (PDQ®)–Patient Version. National Cancer Institute. https://www.cancer.gov/types/breast/patient/breast-prevention-pdq. Published October 11, 2022. Accessed April 1, 2023.

Author’s Last name, First name. Conference presentation title. In: Conference Title; Conference Date; Place of Conference.

Example : Smith, J. R. Vitamin D and Bone Health: A Meta-Analysis. In: Proceedings of the Annual Meeting of the American Society for Bone and Mineral Research; September 20-23, 2022; San Diego, CA.

Thesis or dissertation

Author’s Last name, First name. Title of Thesis or Dissertation. Degree level [Doctoral dissertation or Master’s thesis]. University Name; Year.

Example : Wilson, S. A. The Effects of Vitamin D Supplementation on Bone Health in Postmenopausal Women [Doctoral dissertation]. University of California, Los Angeles; 2018.

ASCE (American Society of Civil Engineers) Style

The ASCE (American Society of Civil Engineers) style is commonly used in civil engineering fields. Here are the different reference formats in ASCE style:

Author’s Last name, First name. “Article Title.” Journal Title, volume number, issue number (year): page numbers. DOI or URL (if available).

Example : Smith, J. R. “Evaluation of the Effectiveness of Sustainable Drainage Systems in Urban Areas.” Journal of Environmental Engineering, vol. 146, no. 3 (2020): 04020010. https://doi.org/10.1061/(ASCE)EE.1943-7870.0001668.

Example : McCuen, R. H. Hydrologic Analysis and Design. 4th ed. Upper Saddle River, NJ: Pearson Education; 2013.

Author’s Last name, First name. “Chapter Title.” In: Editor’s Last name, First name, ed. Book Title. Edition number. Place of Publication: Publisher; Year: page numbers.

Example : Maidment, D. R. “Floodplain Management in the United States.” In: Shroder, J. F., ed. Treatise on Geomorphology. San Diego, CA: Academic Press; 2013: 447-460.

Author’s Last name, First name. “Paper Title.” In: Conference Title; Conference Date; Location. Place of Publication: Publisher; Year: page numbers.

Example: Smith, J. R. “Sustainable Drainage Systems for Urban Areas.” In: Proceedings of the ASCE International Conference on Sustainable Infrastructure; November 6-9, 2019; Los Angeles, CA. Reston, VA: American Society of Civil Engineers; 2019: 156-163.

Author’s Last name, First name. “Report Title.” Report number. Place of Publication: Publisher; Year.

Example : U.S. Army Corps of Engineers. “Hurricane Sandy Coastal Risk Reduction Program, New York and New Jersey.” Report No. P-15-001. Washington, DC: U.S. Army Corps of Engineers; 2015.

CSE (Council of Science Editors) Style

The CSE (Council of Science Editors) style is commonly used in the scientific and medical fields. Here are the different reference formats in CSE style:

Author’s Last name, First Initial. Middle Initial. “Article Title.” Journal Title. Year;Volume(Issue):Page numbers.

Example : Smith, J.R. “Evaluation of the Effectiveness of Sustainable Drainage Systems in Urban Areas.” Journal of Environmental Engineering. 2020;146(3):04020010.

Author’s Last name, First Initial. Middle Initial. Book Title. Edition number. Place of Publication: Publisher; Year.

Author’s Last name, First Initial. Middle Initial. “Chapter Title.” In: Editor’s Last name, First Initial. Middle Initial., ed. Book Title. Edition number. Place of Publication: Publisher; Year:Page numbers.

Author’s Last name, First Initial. Middle Initial. “Paper Title.” In: Conference Title; Conference Date; Location. Place of Publication: Publisher; Year.

Example : Smith, J.R. “Sustainable Drainage Systems for Urban Areas.” In: Proceedings of the ASCE International Conference on Sustainable Infrastructure; November 6-9, 2019; Los Angeles, CA. Reston, VA: American Society of Civil Engineers; 2019.

Author’s Last name, First Initial. Middle Initial. “Report Title.” Report number. Place of Publication: Publisher; Year.

Bluebook Style

The Bluebook style is commonly used in the legal field for citing legal documents and sources. Here are the different reference formats in Bluebook style:

Case citation

Case name, volume source page (Court year).

Example : Brown v. Board of Education, 347 U.S. 483 (1954).

Statute citation

Name of Act, volume source § section number (year).

Example : Clean Air Act, 42 U.S.C. § 7401 (1963).

Regulation citation

Name of regulation, volume source § section number (year).

Example: Clean Air Act, 40 C.F.R. § 52.01 (2019).

Book citation

Author’s Last name, First Initial. Middle Initial. Book Title. Edition number (if applicable). Place of Publication: Publisher; Year.

Example: Smith, J.R. Legal Writing and Analysis. 3rd ed. New York, NY: Aspen Publishers; 2015.

Journal article citation

Author’s Last name, First Initial. Middle Initial. “Article Title.” Journal Title. Volume number (year): first page-last page.

Example: Garcia, C. “The Right to Counsel: An International Comparison.” International Journal of Legal Information. 43 (2015): 63-94.

Website citation

Author’s Last name, First Initial. Middle Initial. “Page Title.” Website Title. URL (accessed month day, year).

Example : United Nations. “Universal Declaration of Human Rights.” United Nations. https://www.un.org/en/universal-declaration-human-rights/ (accessed January 3, 2023).

Oxford Style

The Oxford style, also known as the Oxford referencing system or the documentary-note citation system, is commonly used in the humanities, including literature, history, and philosophy. Here are the different reference formats in Oxford style:

Author’s Last name, First name. Book Title. Place of Publication: Publisher, Year of Publication.

Example : Smith, John. The Art of Writing. New York: Penguin, 2020.

Author’s Last name, First name. “Article Title.” Journal Title volume, no. issue (year): page range.

Example: Garcia, Carlos. “The Role of Ethics in Philosophy.” Philosophy Today 67, no. 3 (2019): 53-68.

Chapter in an edited book citation

Author’s Last name, First name. “Chapter Title.” In Book Title, edited by Editor’s Name, page range. Place of Publication: Publisher, Year of Publication.

Example : Lee, Mary. “Feminism in the 21st Century.” In The Oxford Handbook of Feminism, edited by Jane Smith, 51-69. Oxford: Oxford University Press, 2018.

Author’s Last name, First name. “Page Title.” Website Title. URL (accessed day month year).

Example : Jones, David. “The Importance of Learning Languages.” Oxford Language Center. https://www.oxfordlanguagecenter.com/importance-of-learning-languages/ (accessed 3 January 2023).

Dissertation or thesis citation

Author’s Last name, First name. “Title of Dissertation/Thesis.” PhD diss., University Name, Year of Publication.

Example : Brown, Susan. “The Art of Storytelling in American Literature.” PhD diss., University of Oxford, 2020.

Newspaper article citation

Author’s Last name, First name. “Article Title.” Newspaper Title, Month Day, Year.

Example : Robinson, Andrew. “New Developments in Climate Change Research.” The Guardian, September 15, 2022.

AAA (American Anthropological Association) Style

The American Anthropological Association (AAA) style is commonly used in anthropology research papers and journals. Here are the different reference formats in AAA style:

Author’s Last name, First name. Year of Publication. Book Title. Place of Publication: Publisher.

Example : Smith, John. 2019. The Anthropology of Food. New York: Routledge.

Author’s Last name, First name. Year of Publication. “Article Title.” Journal Title volume, no. issue: page range.

Example : Garcia, Carlos. 2021. “The Role of Ethics in Anthropology.” American Anthropologist 123, no. 2: 237-251.

Author’s Last name, First name. Year of Publication. “Chapter Title.” In Book Title, edited by Editor’s Name, page range. Place of Publication: Publisher.

Example: Lee, Mary. 2018. “Feminism in Anthropology.” In The Oxford Handbook of Feminism, edited by Jane Smith, 51-69. Oxford: Oxford University Press.

Author’s Last name, First name. Year of Publication. “Page Title.” Website Title. URL (accessed day month year).

Example : Jones, David. 2020. “The Importance of Learning Languages.” Oxford Language Center. https://www.oxfordlanguagecenter.com/importance-of-learning-languages/ (accessed January 3, 2023).

Author’s Last name, First name. Year of Publication. “Title of Dissertation/Thesis.” PhD diss., University Name.

Example : Brown, Susan. 2022. “The Art of Storytelling in Anthropology.” PhD diss., University of California, Berkeley.

Author’s Last name, First name. Year of Publication. “Article Title.” Newspaper Title, Month Day.

Example : Robinson, Andrew. 2021. “New Developments in Anthropology Research.” The Guardian, September 15.

AIP (American Institute of Physics) Style

The American Institute of Physics (AIP) style is commonly used in physics research papers and journals. Here are the different reference formats in AIP style:

Example : Johnson, S. D. 2021. “Quantum Computing and Information.” Journal of Applied Physics 129, no. 4: 043102.

Example : Feynman, Richard. 2018. The Feynman Lectures on Physics. New York: Basic Books.

Example : Jones, David. 2020. “The Future of Quantum Computing.” In The Handbook of Physics, edited by John Smith, 125-136. Oxford: Oxford University Press.

Conference proceedings citation

Author’s Last name, First name. Year of Publication. “Title of Paper.” Proceedings of Conference Name, date and location: page range. Place of Publication: Publisher.

Example : Chen, Wei. 2019. “The Applications of Nanotechnology in Solar Cells.” Proceedings of the 8th International Conference on Nanotechnology, July 15-17, Tokyo, Japan: 224-229. New York: AIP Publishing.

Example : American Institute of Physics. 2022. “About AIP Publishing.” AIP Publishing. https://publishing.aip.org/about-aip-publishing/ (accessed January 3, 2023).

Patent citation

Author’s Last name, First name. Year of Publication. Patent Number.

Example : Smith, John. 2018. US Patent 9,873,644.

References Writing Guide

Here are some general guidelines for writing references:

• Follow the citation style guidelines: Different disciplines and journals may require different citation styles (e.g., APA, MLA, Chicago). It is important to follow the specific guidelines for the citation style required.
• Include all necessary information : Each citation should include enough information for readers to locate the source. For example, a journal article citation should include the author(s), title of the article, journal title, volume number, issue number, page numbers, and publication year.
• Use proper formatting: Citation styles typically have specific formatting requirements for different types of sources. Make sure to follow the proper formatting for each citation.
• Order citations alphabetically: If listing multiple sources, they should be listed alphabetically by the author’s last name.
• Be consistent: Use the same citation style throughout the entire paper or project.
• Check for accuracy: Double-check all citations to ensure accuracy, including correct spelling of author names and publication information.
• Use reputable sources: When selecting sources to cite, choose reputable and authoritative sources. Avoid sources that are biased or unreliable.
• Include all sources: Make sure to include all sources used in the research, including those that were not directly quoted but still informed the work.
• Use online tools : There are online tools available (e.g., citation generators) that can help with formatting and organizing references.

Purpose of References in Research

References in research serve several purposes:

• To give credit to the original authors or sources of information used in the research. It is important to acknowledge the work of others and avoid plagiarism.
• To provide evidence for the claims made in the research. References can support the arguments, hypotheses, or conclusions presented in the research by citing relevant studies, data, or theories.
• To allow readers to find and verify the sources used in the research. References provide the necessary information for readers to locate and access the sources cited in the research, which allows them to evaluate the quality and reliability of the information presented.
• To situate the research within the broader context of the field. References can show how the research builds on or contributes to the existing body of knowledge, and can help readers to identify gaps in the literature that the research seeks to address.

Importance of References in Research

References play an important role in research for several reasons:

• Credibility : By citing authoritative sources, references lend credibility to the research and its claims. They provide evidence that the research is based on a sound foundation of knowledge and has been carefully researched.
• Avoidance of Plagiarism : References help researchers avoid plagiarism by giving credit to the original authors or sources of information. This is important for ethical reasons and also to avoid legal repercussions.
• Reproducibility : References allow others to reproduce the research by providing detailed information on the sources used. This is important for verification of the research and for others to build on the work.
• Context : References provide context for the research by situating it within the broader body of knowledge in the field. They help researchers to understand where their work fits in and how it builds on or contributes to existing knowledge.
• Evaluation : References provide a means for others to evaluate the research by allowing them to assess the quality and reliability of the sources used.

Advantages of References in Research

There are several advantages of including references in research:

• Acknowledgment of Sources: Including references gives credit to the authors or sources of information used in the research. This is important to acknowledge the original work and avoid plagiarism.
• Evidence and Support : References can provide evidence to support the arguments, hypotheses, or conclusions presented in the research. This can add credibility and strength to the research.
• Reproducibility : References provide the necessary information for others to reproduce the research. This is important for the verification of the research and for others to build on the work.
• Context : References can help to situate the research within the broader body of knowledge in the field. This helps researchers to understand where their work fits in and how it builds on or contributes to existing knowledge.
• Evaluation : Including references allows others to evaluate the research by providing a means to assess the quality and reliability of the sources used.
• Ongoing Conversation: References allow researchers to engage in ongoing conversations and debates within their fields. They can show how the research builds on or contributes to the existing body of knowledge.

About the author

Muhammad Hassan

Researcher, Academic Writer, Web developer

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Thursday, February 23: The Clark Library is closed today.

APA Style (7th Edition) Citation Guide: Journal Articles

• Introduction
• Journal Articles
• Magazine/Newspaper Articles
• Books & Ebooks
• Government & Legal Documents
• Biblical Sources
• Secondary Sources
• Films/Videos/TV Shows
• How to Cite: Other
• Additional Help

Table of Contents

Journal article from library database with doi - one author, journal article from library database with doi - multiple authors, journal article from a website - one author.

Journal Article- No DOI

Note: All citations should be double spaced and have a hanging indent in a Reference List.

A "hanging indent" means that each subsequent line after the first line of your citation should be indented by 0.5 inches.

This Microsoft support page contains instructions about how to format a hanging indent in a paper.

• APA 7th. ed. Journal Article Reference Checklist

If an item has no author, start the citation with the article title.

When an article has one to twenty authors, all authors' names are cited in the References List entry. When an article has twenty-one or more authors list the first nineteen authors followed by three spaced ellipse points (. . .) , and then the last author's name. Rules are different for in-text citations; please see the examples provided.

Cite author names in the order in which they appear on the source, not in alphabetical order (the first author is usually the person who contributed the most work to the publication).

Italicize titles of journals, magazines and newspapers. Do not italicize or use quotation marks for the titles of articles.

Capitalize only the first letter of the first word of the article title. If there is a colon in the article title, also capitalize the first letter of the first word after the colon.

If an item has no date, use the short form n.d. where you would normally put the date.

Volume and Issue Numbers

Italicize volume numbers but not issue numbers.

Retrieval Dates

Most articles will not need these in the citation. Only use them for online articles from places where content may change often, like a free website or a wiki.

Page Numbers

If an article doesn't appear on continuous pages, list all the page numbers the article is on, separated by commas. For example (4, 6, 12-14)

Library Database

Do not include the name of a database for works obtained from most academic research databases (e.g. APA PsycInfo, CINAHL) because works in these resources are widely available. Exceptions are Cochrane Database of Systematic Reviews, ERIC, ProQuest Dissertations, and UpToDate.

Include the DOI (formatted as a URL: https://doi.org/...) if it is available. If you do not have a DOI, include a URL if the full text of the article is available online (not as part of a library database). If the full text is from a library database, do not include a DOI, URL, or database name.

In the Body of a Paper

Books, Journals, Reports, Webpages, etc.: When you refer to titles of a “stand-alone work,” as the APA calls them on their APA Style website, such as books, journals, reports, and webpages, you should italicize them. Capitalize words as you would for an article title in a reference, e.g., In the book Crying in H Mart: A memoir , author Michelle Zauner (2021) describes her biracial origin and its impact on her identity.

Article or Chapter: When you refer to the title of a part of a work, such as an article or a chapter, put quotation marks around the title and capitalize it as you would for a journal title in a reference, e.g., In the chapter “Where’s the Wine,” Zauner (2021) describes how she decided to become a musician.

The APA Sample Paper below has more information about formatting your paper.

• APA 7th ed. Sample Paper

Author's Last Name, First Initial. Second Initial if Given. (Year of Publication). Title of article: Subtitle if any. Name of Journal, Volume Number (Issue Number), first page number-last page number. https://doi.org/doi number

Smith, K. F. (2022). The public and private dialogue about the American family on television: A second look. Journal of Media Communication, 50 (4), 79-110. https://doi.org/10.1152/j.1460-2466.2000.tb02864.x

Note: The DOI number is formatted as a URL: https://doi.org/10.1152/j.1460-2466.2000.tb02864.xIf

In-Text Paraphrase:

(Author's Last Name, Year)

Example: (Smith, 2000)

In-Text Quote:

(Author's Last Name, Year, p. Page Number)

Example: (Smith, 2000, p. 80)

Author's Last Name, First Initial. Second Initial if Given., & Last Name of Second Author, First Initial. Second Initial if Given. (Year of Publication). Title of article: Subtitle if any. Name of Journal, Volume Number (Issue Number), first page number-last page number. https://doi.org/doi number

Note: Separate the authors' names by putting a comma between them. For the final author listed add an ampersand (&) after the comma and before the final author's last name.

Note: In the reference list invert all authors' names; give last names and initials for only up to and including 20 authors. When a source has 21 or more authors, include the first 19 authors’ names, then three ellipses (…), and add the last author’s name. Don't include an ampersand (&) between the ellipsis and final author.

Note : For works with three or more authors, the first in-text citation is shortened to include the first author's surname followed by "et al."

Reference List Examples

Two to 20 Authors

Case, T. A., Daristotle, Y. A., Hayek, S. L., Smith, R. R., & Raash, L. I. (2011). College students' social networking experiences on Facebook. Journal of Applied Developmental Psychology, 3 (2), 227-238. https://doi.org/10.1016/j.appdev.2008.12.010

21 or more authors

Kalnay, E., Kanamitsu, M., Kistler, R., Collins, W., Deaven, D., Gandin, L., Iredell, M., Saha, J., Mo, K. C., Ropelewski, C., Wang, J., Leetma, A., . . . Joseph, D. (1996). The NCEP/NCAR 40-year reanalysis project. Bulletin of the American Meteorological Society , 77 (3), 437-471. https://doi.org/10.1175/1520-0477(1996)077<0437:TNYRP>2.0.CO;2

In-Text Citations

Two Authors/Editors

(Case & Daristotle, 2011)

Direct Quote: (Case & Daristotle, 2011, p. 57)

Three or more Authors/Editors

(Case et al., 2011)

Direct Quote: (Case et al., 2011, p. 57)

Author's Last Name, First Initial. Second Initial if Given. (Year of Publication). Title of article: Subtitle if any.  Name of Journal, Volume Number (Issue Number if given). URL

Flachs, A. (2010). Food for thought: The social impact of community gardens in the Greater Cleveland Area.  Electronic Green Journal, 1 (30). http://escholarship.org/uc/item/6bh7j4z4

Example: (Flachs, 2010)

Example: (Flachs, 2010, Conclusion section, para. 3)

Note: In this example there were no visible page numbers or paragraph numbers; in this case you can cite the section heading and the number of the paragraph in that section to identify where your quote came from. If there are no page or paragraph numbers and no marked section, leave this information out.

Journal Article - No DOI

Author's Last Name, First Initial. Second Initial if Given. (Year of Publication). Title of article: Subtitle if any.  Name of Journal, Volume Number (Issue Number), first page number-last page number. URL [if article is available online, not as part of a library database]

Full-Text Available Online (Not as Part of a Library Database):

Steinberg, M. P., & Lacoe, J. (2017). What do we know about school discipline reform? Assessing the alternatives to suspensions and expulsions.  Education Next, 17 (1), 44–52.  https://www.educationnext.org/what-do-we-know-about-school-discipline-reform-suspensions-expulsions/

Example: (Steinberg & Lacoe, 2017)

(Author's Last Name, Year, p. Page number)

Example: (Steinberg & Lacoe, 2017, p. 47)

Full-Text Available in Library Database:

Jungers, W. L. (2010). Biomechanics: Barefoot running strikes back.  Nature, 463 (2), 433-434.

Example: (Jungers, 2010)

Example: (Jungers, 2010, p. 433)

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APA Style 7th Edition

• Student Paper
• Professional Paper
• In-Text Citations
• Reference Citations
• Additional Resources

Audio Recording

Album  • Track   • Radio   • Spoken Word

See also Podcasts .

Needed Information

• If no artist, author, or speaker is listed move the title of the work of art into the place of the author (before the date).
• If there is no date associated with the work use the designation 'n.d.' in place of the date
• If the work is untitled, in square brackets give a description of the work
• Type of work - album, song, audiobook, audio track, interview, speech audio recording
• Label, publisher, website, content holder
• If the item is in physical format give the location (generally city, state, nation)
• If the item is online give the URL

Barnum, P. T. (2011). The art of money getting [Audiobook]. LibriVox. (Original work published in 1880) https://librivox.org/the-art-of-money-getting-by-p-t-barnum/

Bob Marley and the Wailers. (1984). Legend [Album]. Island; Tuff Gong.

Brown, B. (2018). Dare to lead: Brave work, tough conversations, whole hearts [Audiobook]. Random House Audio.

Mozart, W. A. (2008). Mozart: The symphonies [Album recorded by the Prague Chamber Orchestra]. Telarc. (Original works composed 1764-1778)

Panrucker, S. (2015). Hello my name is Simon Panrucker [Album]. Free Music Archive. https://freemusicarchive.org/music/Simon_Panrucker/Hello_My_Name_Is_Simon_Panrucker

van Schalkwyk, W. (Pianist), & Faganel, G. (Cellist). (2018, February 7). Faculty recital [Album]. University of Northern Colorado.

Verdi, G. (2015). Requiem mass [Album recorded by the UNC Symphony Orchestra & Choirs]. University of Northern Colorado. (Original work composed ca. 1874)

Wonder, S. (1976). Songs in the key of life [Album]. Tamla.

Beyoncé. (2020). Black parade [Song]. Park; Columbia.

Creedence Clearwater Revival. (1969). Fortunate son [Song]. On Willy and the poor boys . Fantasy.

Manson, M. (2016). The tyranny of exceptionalism [Audio track] . In The subtle art of not giving a f*ck: A counterintuitive approach to living a good life . HarperCollins; Blackstone Audio.

Roberts, D. (2021). Race [Audio track]. In N. Hannah-Jones, C. Roper, I. Silverman, & J. Silverstein (Eds.), The 1619 project . One World.

Xavier Cugat and His Orchestra. (1953). Mi prieta [Song]. On Mambo . Mercury; Internet Archive. https://archive.org/details/lp_mambo_xavier-cugat-and-his-orchestra

Coates, E. J. (2019, August 20). Audio recording of interview with Elaine J. Coates [Interview]. University of Maryland Libraries, Special Collections and University Archives. https://archives.lib.umd.edu/repositories/2/digital_objects/18120

Saunders, V. (1990, December 1). The living memory of the Jewish community: Saunders, Vernon (Part 3) [Interview]. British Library Sounds. https://sounds.bl.uk/Oral-history/Jewish-Holocaust-survivors/021M-C0410X0101XX-0300V0

Scroggins, B. (n.d.). Bessie Scroggins [Interview]. University of Northern Colorado, Archives & Special Collections @ Digital UNC. https://digarch.unco.edu/islandora/object/cogru:4095

Wynne, S. W. (1931, November 30). Diet and health with Dr. Shirley W. Wynne, health commissioner [Interview]. WYNC, NYPR Archive Collections. https://www.wnyc.org/story/1140-a-m-diet-and-health-dr-shirley-w-wynne-health-commissioner

Gore, K. (2000). [Kristen Gore, daughter of Tipper Gore, gives a speech about her mother] [Speech audio recording]. Michigan State University Libraries, East Lansing, MI, United States.

Harding, W. G. (1920). National and Americanism [Speech audio recording]. Library of Congress. https://www.loc.gov/item/2004650664/

Poehler, A. (2011, May 26). Harvard University class day commencement address [Speech audio recording]. American Rhetoric. https://www.americanrhetoric.com/speeches/amypoehlerharvardcommencement.htm

Ruth, G. H., Jr. (1947, April 27). Dying Babe Ruth addresses fans [Speech audio recording]. History. https://www.history.com/speeches/dying-babe-ruth-addresses-fans

Truman, H. S. (1934, July 28). Judge Harry S. Truman Speech, Springfield, Missouri (SR84-1) [Speech audio recording]. Harry S. Truman Library & Museum, Independence, MO, United States.

When discussing an entire blog in your paper (and not indicating a specific idea, fact, or document) it is acceptable to simply include the URL of the website in parentheses within your writing.  If you are referring to a specific piece of information or directly quoting information on a blog, a text and reference citation are required .

The blog  Just a Colorado Gal  (http://www.justacoloradogal.com/) covers not only hiking gear, routes, basics, and specifics, but also follow’s the life of the blogger.

Authors of academic papers can find useful tips and answers to APA questions not covered in the  Publication Manual  on the  APA Style Blog  (http://blog.apastyle.org/apastyle/).

With the tag line 'writer. professor. part-time hippie.' the  Stacia L. Brown  blog (http://stacialbrown.com/) offers readers current news topics with a human element and a humane eye.

Adventures of a Labor Nurse: The Highs and Lows of Labor and Delivery  blog (http://adventuresofalabornurse.com/) looks at the nursing profession and the people with humor and grace.

Information Needed

• Date of Post (Year, Month Day)
• Title of Post
• Title of Blog

Hoffman, C. (2022, March 3). Your wif-fi is in Google and Microsoft's databases: Should you care? How-To Geek .  https://www.howtogeek.com/788837/your-wi-fi-info-is-in-google-and-microsofts-databases-should-you-care/

McAdoo, T. (2020, March 16). How to create an APA Style reference for a canceled conference presentation. APA Style.   https://apastyle.apa.org/blog/canceled-conferences

Our fave podcasts + audio books for holiday travel. (2019, November 19). Love Sweat Fitness.   https://lovesweatfitness.com/our-fave-podcasts-audio-books-for-holiday-travel/

Comment on Blog Entry

• Author screenname/username or proper name
• Date of comment (Year, Month Day)
• Title of comment or first 20 words of comment
• Title of blog

Azavedo, M. (2021, March 2). Your approach excites me, is what I too do. I really want to get my hands on the book you [Comment on the article “Creative writing for social research”]. The Research Whisperer. https://researchwhisperer.org/2021/03/02/creative-writing-for-social-research/

Jonathan. (2013, January 6). It’s not that work is less important, but that you can get it done efficiently, the right way [Comment on the article “Do you have an overwork problem?”]. Get a life, PhD. http://getalifephd.blogspot.com/2013/01/do-you-have-overwork-problem.html

Woshiernog. (2022, March 16). Why are people so gung-ho about talking about sexual things to K-3 rd graders and hiding those thing from the student parents? [Comment on the article “Marvel Studio denounces ‘Don’t Say Gay’ bill as Disney employees plan walkout”]. Gizmodo. https://gizmodo.com/marvel-studios-disney-florida-lgbtq-bill-backlash-1848660759

Authored Book • Edited Book   • Anthology   • Book Edition   • eBook with DOI   • eBook from Library Dat abase   • Other eBooks

If citing only a chapter from an edited book, see examples for chapters in edited books .

• Author(s) or editor(s)
• Year of publication
• Title of book
• Publisher Name (if the author and the publisher is the same, omit the publisher)
• If not the first edition of a book: Edition number
• If part of a multi-volume set: Volume number
• If an ebook: DOI or URL, unless ebook is from library database

Authored Book

Cabaniss, A. (1970). Liturgy and literature: Selected Essays . University of Alabama Press.

Chandler, D., & Werther, W. B., Jr. (2014). Strategic corporate social responsibility: Stakeholders, globalization, and sustainable value creation (3rd ed.). SAGE Publications.

Rhodes, C. (2020). Disturbing business ethics: Emmanuel Levinas and the politics of organization . Routledge.

Edited Book

Felker, G. M., & Mann, D. L. (Eds.). (2020). Heart failure: A companion to Braunwald's heart disease . Elsevier.

Garnett, S., Latch, P., Lindenmayer, D., & Woinarski, J. (Eds.). (2018). Recovering threatened species: A book of hope . CSIRO Publishing.

Pappas, G., & Guajardo, M. (Eds.). (1993). Colorado Hispanics: A report of selected social concerns .    Latin American Research and Service Agency.

125th anniversary anthology, 1839-1964: A sampling of reading tastes from the lists of an American publisher with a brief historical commentary. (1964). Dodd, Mead & Co.

Garnett, R., Valle'e, L., & Brandl, A. (Eds.). (1902). The universal anthology: A collection of the best literature, ancient, medieval and modern, with biographical and explanatory notes (Westminster Ed., Vol. 33). Merrill & Baker.

Gates, H. L., Jr., & Smith, V. (Eds.). (2014). The Norton anthology of African American literature (3rd ed., Vol. 2). W. W. Norton & Company.

Book Edition

Finkelnburg, W. (1964). Structure of matter (W. Finkenburg & O. Matossi-Riechmeier, Trans., 9th/10th ed.). Springer.

Reid, A., Tu, S., Port, K. L. (2018). Fundamentals of United States intellectual property law: Copyright, patent, and trademark (6th ed.). Kluwer Law International.

Turekian, K. K. (2010). Marine chemistry and geochemistry: A derivative of encyclopedia of ocean sciences (2nd ed.). Academic Press.

eBook with DOI

Goldman, M. B., Troisi, R., & Rexrode, K. M. (2013). Women and health (2nd ed.). Elsevier. https://doi.org/10.1016/C2009-0-01962-X

Jones, P., Miles, D., & Gopalkrishnan, N. (2019). Intercultural learning: Critical preparation for international student travel. UTS ePRESS. https://doi.org/10.5130/978-0-9945039-9-2

Kersten, F. (1997). Galileo and the 'invention' of opera: A study in the phenomenology of consciousness . Springer: https://doi.org/10.1007/978-94-015-8931-4

eBook from Library Database

Other eBooks (no DOI, not from a library database)

Curnow, K. (2018). The bright continent: African art history . MSL Academic Endeavors.  https://pressbooks.ulib.csuohio.edu/bright-continent/

Doyle, G. R., & McCuthcheon, J. A. (2015). Clinical procedures for safer patient care . British Columbia Institute of Technology.  https://opentextbc.ca/clinicalskills/

Vatsyayana. (2009). The kama sutra of Vatsyayana: Translated from the Sanscrit in seven parts with preface, introduction and concluding remarks (S. P. Bhide, R. F. Burton, & B. Indrajit, Trans.). Project Gutenberg.  (Original work published in 1883)  https://www.gutenberg.org/ebooks/27827

Book Chapter ♦ Reference Work Entry

Book Chapter • Handbook Section/Chapter  •  Dictionary Entry   • Encyclopedia Entry  • Wikipedia Entry

Generally, only cite book chapters when the book has editors and chapters are by different authors or groups of authors. When citing a book with authors but no editors, cite the whole book in the reference list and, if appropriate, give the chapter number in the text citation.

• Chapter author(s) 
• Title of chapter, section, or author
• Book editor(s)
• Page numbers of chapter, section, or author

For information of when to use a DOI, URL, or neither, see the Book section.

Edited Book Chapter

Fasina, A. (2015). Case 3: Altered mental status. In Y. Okuda & B. P. Nelson (Eds.), Emergency medicine oral board review illustrated (2nd ed., pp. 47-50). Cambridge University Press. https://amzn.to/2yFID2P

Pegoraro, A., Scott, O., & Burch, L. M. (2017). Strategic use of Facebook to build brand awareness: A case study of two national sport organizations. In Information Resources Management Association (Ed.), Sports, media, marketing, and management: Breakthroughs in research and practice (pp. 97-118). IGI Global. 

Handbook Section/Chapter

Lin, W. (2020). Participatory geographic information systems in visual research. In L. Pauwels & D. Mannay (Eds)., The SAGE handbook of visual research methods (2nd ed., pp. 173-185). SAGE Publications. 

For online reference works that are continuously updated , such as the online version of the Merriam-Webster Dictionary, the publication date should be recorded as n.d. (no date) and the date you looked at the online article is placed before the URL in the citation.

• Dictionary entry examples: #1 and #2
• Encyclopedia entry examples: #1 and #3

Even some more 'official' dictionaries and encyclopedias are updated in an on-going basis and should follow the rule above. For instance, the first example under Encyclopedias is called a 'living edition' even though it has a DOI, ISBN, and publisher. Therefore, the citation requires that 'no date' be indicated in the publication date and retrieval information is included before the URL.

Because Wikipedia keeps copies of each version of each article, do not use 'no date' in place of the publication date, nor include retrieval date information. 

Dictionary Entry

Encyclopedia Entry

Reynolds, C. R., Vannest, K. J., & Fletcher-Janzen, E. (2014). Visual-motor and visual-perceptual problems.  In Encyclopedia of special education, Vol. 4: A reference for the education of children, adolescents, and adults with disabilities and other exceptional individuals (4th ed., pp. 2727-2728). Wiley. 

Wikipedia Entry

To find the date of the article you wish to cite, click on " View History " in the top, right-hand corner of the Wikipedia page, and select the most current version of the article by clicking on the most current date. The URL will now have a series of numbers at the end, indicating an archived version of the Wikipedia article that gives reference to the exact version of the article you accessed.

• Title of systematic review

Foxcroft, D. R., Moreira, M. T., Almeida Santimano, N. M. L., & Smith, L. A. (2015). Social norms information for alcohol misuse in university and college students. Cochrane Database of Systematic Reviews . https://doi.org/10.1002/14651858.CD006748.pub4

Molyneaux, E., Howard, L. M., McGeown, H. R., Karia, A. M., & Trevillion, K. (2014). Antidepressant treatment for postnatal depression. Cochrane Database of Systematic Reviews . https://doi.org/10.1002/14651858.CD002018.pub2

Pellicori, P., Doolub, G., Wong, C. M., Lee, K. S., Mangion, K., Ahmad, M., Berry, C., Squire, I., Lambiase, P. D., Lyon, A., McConnachie, A., Taylor, R. S., & Cleland, J. G. F. (2021). COVID-19 and its cardiovascular effects: A systematic review of prevalence studies. Cochrane Database of Systematic Reviews . https://doi.org/10.1002/14651858.CD013879

If citing a canceled presentation or a conference that was planned for in-person attendance but changed to virtual, see the APA Blog article How to Create an APA Style Reference for a Canceled Conference Presentation . 

• Presenter(s)
• Dates of conference (generally Year, Month Day-Day)
• Title of session
• Type of session (Conference session, Paper presentation, Poster presentation, Plenary session, Keynote, Workshop, etc.)
• Name of conference
• Generally City, State, Nation or equivalent
• If a completely virtual conference, do not include a location
• URL (if available)

Conference Session - In-Person or Hybrid Conference

Blackman, C., Fore, I., & Skinner, K. (2016, May 16-19). A new dimension for team science – individual and system elements in collaboration [Workshop]. Science of Team Science (SciTS) 2016 Conference. https://bit.ly/3Il0gmn

Gustetic, J. (2019, September 21-24). Opening session [Keynote]. 2019 ASTC Annual Conference. Toronto, Ontario, Canada. https://www.astc.org/wp-content/uploads/2020/03/2019ASTCAnnualConferenceProgram.pdf

Radford, M. L., Kitzie, V., Mikitish, S., Floegel, D., & Silipigni Connaway, L. (2019, April 10-13). Trending now: Recasting services to support scholarly identity work [Paper presentation]. ACRL 2019. Cleveland, OH, United States. https://www.ala.org/acrl/sites/ala.org.acrl/files/content/conferences/confsandpreconfs/2019/acrl2019_program.pdf

Sablan, J., Edwards, K., Wiles, L. J., Guillen, C., & Bai, Z. (2018, March 3-7). Collaboration across units: Lessons shared in support of undergraduate and graduate student transitional experiences [Poster presentation]. 2018 NASPA Annual Conference. Philadelphia, PA, United States. https://conference.naspa.org/images/uploads/2018-NASPA-book-web.pdf

Smith, K. (2016, June 6-7). Libraries & copyright: The past and present [Conference session]. Kraemer Copyright Conference. Colorado Springs, CO, United States. https://copyright.uccs.edu/kraemerconference/archives/sessions2016

Conference Session - Virtual Only Conference

Chow, K. (2022, January 31-February). Propelling Java at Alibaba scale [Plenary session]. CMG IMPACT 2022. https://cmgimpact.com/schedule2022/

Hacker, D. (2022, February 24-25). Deprived at both ends: Women under secular and religious family law [Keynote]. Fifth International Conference on the Future of Women. https://futurewomenconference.com/#

Many, A., Parks, J., Zaback, K., & Zinth, J. (2021, October 18-19). Building OER capacity in the Midwest: Supporting grassroots efforts and statewide collaboration [Conference session]. Open Education Conference. https://opened21.sched.com/

Ybarra, J., Anderson, J., & Karr, S. (2021, April 18). The mediating role of self-efficacy on the math anxiety-performance relationship [Poster presentation]. University of Northern Colorado Research Day 2021. https://www.unco.edu/honors-scholars-leadership/aew/researchdayposters.aspx

• Year of publication/year of posting/year of release
• Title of data set
• Version number, if given
• DOI or URL, if an online data set

Bywater-Reyes, S., Diehl, R. M., & Wilcox, A. C. (2018). T he influence of a vegetated bar on channel-bend flow dynamics (no. 5) [Data set]. University of Northern Colorado, Scholarship & Creative Works @ Digital UNC. https://digscholarship.unco.edu/esd_data_2018/16/

Doornwaard, S. M., ter Bogt, T. F. M., Reitz, E., & van den Eijnden, R. J. J. M. (2016). Sex-related online behaviors, perceived peer norms and adolescents’ experience with sexual behavior: Testing an integrative model [Data set]. Dryad. https://doi.org/10.5061/dryad.96bc0

National Center for State Courts. (1984). Criminal case processing in metropolitan courts, 1976 [Data set]. University of Michigan, Institute for Social Research.

National Oceanographic Data Center. (1988). Environmental buoy data [Data set]. National Oceanic and Atmospheric Administration.

Pastor, D., Patterson, C., & Goldberg, A. (2021). Anticipated future political participation: A college student sample (Version 1) [Data set, code book, and instrument]. ICPSR. https://www.openicpsr.org/openicpsr/project/134261

A digital object identifier (DOI) is an alphanumeric code that is assigned to content to provide a persistent identifier (like a social security number for articles and chapters and other content). A DOI acts as a locator - helping individuals find articles and chapters cited in bibliographies. DOIs are preferable to URLs because even if the URL for an article breaks in the future, the DOI will remain constant.

DOIs and APA Style

In APA-style reference citations, always express the DOI as a URL ( see below ). This may sound confusing (after all, DOIs different than URLS), but expressing a DOI as a URL allows readers to more easily access the document you cited. DOIs are commonly seen on born-digital content, but may also be included in the print version of content. DOIs always begin with 10; however, a DOI can be expressed as a URL, where https://doi.org/ appears in front of the DOI. If you find a DOI on a source you are citing that does not include https://doi.org/ as a prefix, add it to the DOI for the APA citation. It is best to copy and paste the DOI from digital content to your bibliography so that there are no transcription errors - but don't forget to change the font and font size to match the rest of your paper!  

DOI without URL prefix 10.1111/j.1471-8847.2007.00193.x

same DOI with URL prefix added https://doi.org/ 10.1111/j.1471-8847.2007.00193.x

1. The DOI should be listed on the first page of a journal article . It is sometimes more difficult to find a DOI on a book or book chapter – check the title page verso .  The DOI may or may not be prefaced with the letters DOI.

DOI on the Article First Page - Example 1    DOI on the Article First Page - Example 2   

2. DOIs are often included in database records .  Thus, when searching a library database like Academic Search Premier, SpringerLink, or Summon, if a DOI is assigned to an article, book, or book chapter, the DOI will be included in the database record.

DOI in a Database Record - Example 1 DOI in a Database Record - Example 2

3. DOIs may also be found in the bibliography of an article – as authors are now using DOIs as a citation tool. If you find a DOI in a bibliography and want to find the actual article, book, or book chapter (or at least further citation information), you need to use a DOI resolver ( see http://dx.doi.org/ ).

Film, Television & Video

Feature Film • Documentary Film   • Educational Film   • Television Series   • Television Episode   • TED Talks   • YouTube   • Vimeo  • Webinar

Feature Film

• Director(s)
• Year of release
• Film title - if non-English film, include both the title in the original language and the English version of title)
• Format type - it is not incorrect to include the format type always; but it is necessary to include the format type if the format provides additional content, such as a DVD with commentary or extras.
• Production company/companies

Anders, A., Rockwell, A., Rodriguez, R., & Tarantino, Q. (Directors). (1995). Four rooms [Film]. A Band Apart.

Capra, F. (Director). (1946). It’s a wonderful life [Film]. Liberty Films.

Fleming, V. (Director). (1939). Gone with the wind [Film]. Selznick International Pictures; Metro-Goldwyn-Mayer.

Gilliam, T. (Director). (1998). Fear and loathing in Las Vegas (Criterion Collection ed.) [Film; Blu-ray disc]. Rhino Films; Summit Entertainment.

Kurosawa, A. (Director). (1954). Shichinin no samurai [Seven samurai] [Film]. Toho.

Renoir, J. (Director). (1950). La règle du jeu [The rules of the game] [Film]. Nouvelle Éditions Française.

Documentary Film

• Film title - if non-English film, include both the title in the original language and the English version of title)

Flaherty, R. J. (Director). (1922). Nanook of the north [Film; documentary]. Pathé Exchange.

Morris, E. (Director). (1988). The thin blue line [Film; documentary]. Miramax Films.

Neville, M. (Director). (2018). Won’t you be my neighbor [Film; documentary]. Tremolo Productions; Impact Partners; Independent Lens.

Peck, R. (Director). (2016). I am not your Negro [Film; documentary DVD]. Velvet Film; Artemis Productions; Close Up Films.

Zhangke, J. (Director). (2020). Yí zhi yóu dào hǎi shuǐ biàn Ián [Swimming out till the sea turns blue] [Film; documentary]. Xstream Pictures.

Educational Film

• Name of database or collection if film is only available through a specific database or collection

Newman, R. D., & Nightingale, J. (Producers). (2012). Videofluoroscopic review of swallowing: Biomechanics, physiology, pathology [Film; educational DVD]. Vision Four Video; Plural Publishing.

McIlwain, C., Fisherkeller, J., Dietrich, E., & Benson, R. (Speakers). (2006). Qualitative research: Methods in the social sciences [Film; educational video]. SAGE Research Methods Video.

Prince, K. (Director). (2019). Some like it hip hop [Theatrical production recording]. ZooNation: The Kate Prince Company. Retrieved from Digital Theatre Plus.

Sartore, J. (Speaker). (2013). The art of travel photography: Six expert lessons [Film; educational DVD]. Teaching Company.

Television Series

• Executive producer(s)
• Years of production - if the series in ongoing, use the word "present" for the latter date
• Title of television series - if non-English film, include both the title in the original language and the English version of title)

Cho, H.-j., & Kim, S.-h. (Executive Producers). (2018-2019). Alhambeura goongjeonui chooeok [Memories of the Alhambra] [TV series]. Chorokbaem Media; Studio Dragon.

Kohan, J., Friedman, L, Hess, S., Herrmann, T., Vinnecour, L, Tannenbaum, N. K., & Burley, M. A. (Executive Producers). Orange is the new black [Netflix TV series]. Titled Productions; Lionsgate Television.

Maher, B. (Creator & Presenter). (2003-present). Real time with Bill Maher [TV series]. Bill Maher Productions; Grad Grey Television; Home Box Office.

Sheldon, L. (Executive Producer). (1961-1966). The Dick Van Dyke show [TV series]. Calvada Productions.

Television Episode

• Writer(s) and Director(s)
• Original air date
• Episode Title 
• Season number, episode number
• Title of television series  - if non-English film, include both the title in the original language and the English version of title)

Dueñas, M. (Writer), Grondona, A. (Writer), Rubio, S. L. (Writer), & Peñafiel, I. (Director). (2013, November 18). El sol siempre vuelve a salir (Season 1, Episode 5) [TV series episode]. In E. Pina & R. Baltanás (Executive Producers), El tiempo entre costuras [The time in between]. Boomerang TV; Atresmedia.

Parker, T. (Writer), Stone, M. (Writer), Goodman, D. R. (Writer), & Stough, E. (Director). (2001, July 11). Scott Tenorman must die [TV series episode]. In T. Parker, M. Stone, B. Graden, D. Liebling, F. C. Agnone, II, B. Howell, & A. Garefino (Executive Producers) South Park . Celluloid Studios; MTV Entertainment Studios; Comedy Parnters.

Williams, R. (Writer), & Bucksey, C. (Director). (2016, December 16). The road less traveled (Season 2, Episode 2) [Amazon Prime TV episode]. In R. Scott, F. Spotnitz, C. Baute, I. D. Hackett, S. Mackinnon, & C. Tricarico (Executive Producers), The man in the high castle . Amazon Studios; Scott Free Productions; Electric Shepherd Productions; Headline Pictures; Bight Light Productions; Picrow; Reunion Pictures.

If the TED Talk recording is found on YouTube, cite as a YouTube video (see examples below).

• Speaker - or the entity posting the video if found on YouTube
• Date - year and month if found on TED website or year, month, and day if found on YouTube
• Title of talk - include the speaker's name if found on YouTube

Robinson, K. (2006, February). Do schools kill creativity? [Video]. TED Conferences. https://www.ted.com/talks/sir_ken_robinson_do_schools_kill_creativity ?

TED. (2015, March 20). Monica Lewinski: The price of shame [Video]. YouTube. https://youtu.be/H_8y0WLm78U

TED. (2015, April 3). Bill Gates: The next outbreak? We’re not read y [Video]. YouTube. https://youtu.be/6Af6b_wyiwI

Urban, T. (2016, February). Inside the mind of a master procrastinator [Video]. TED Conferences. https://www.ted.com/talks/tim_urban_inside_the_mind_of_a_master_procrastinator

• Name of person or entity posting the video (if known)
• Screenname or username of entity posting the video
• Date video was posted (year, month, day)
• Title of video

Drost, H. [Drost Video]. (2017, July 3). How to find your most watched YouTube videos [Video]. YouTube. https://youtu.be/H_HrNWPThiA

Ghate, J. (2020, April 16). How to paint big dot mandala step by step tutorial [Video]. YouTube. https://youtu.be/sSCPMuOoHJo

Kjellberg, F. A. U. [PewDiePie]. (2021, November 5). People break their legs on purpose. Why? [Video]. YouTube. https://youtu.be/H_HrNWPThiA

Pinkfong Baby Shark – Kids’ Songs & Stories. (2016, June 17). Baby shark dance [Video]. YouTube. https://youtu.be/XqZsoesa55w

University of Northern Colorado, University Libraries [UNCLibraries]. (2020, June 12]. APA style 7 th edition: Formatting an APA style paper – student paper in Microsoft Word [Video]. YouTube. https://youtu.be/wBQz_FHhbRg

Art Gallery of Western Australia. (n.d.). Hannah Gadsby at AGWA: E Phillips Fox [Video]. Vimeo. https://vimeo.com/243261903

Brass, M. (2011, August 12). Rocky Mountain National Park [Video]. Vimeo. https://vimeo.com/27620090

Montana Office of Tourism. (n.d.). Indian nations: Cippewa Cree [Video]. Vimeo. https://vimeo.com/74474155

Wolf, M. (2020, August 31). Another hayride [Video]. Vimeo. https://vimeo.com/453421514

If the Webinar recording is found on YouTube, cite as a YouTube video (see example below).

• Speaker(s) - or the entity posting the video if found on YouTube
• Date - year, month, day
• Title of webinar
• Name of entity responsible for recording/posting the webinar if not found on YouTube

Association of Clinicians for the Underserved. (2021, June 30). Managing in the time of COVID-19 & beyond – diversity, equity, & inclusion [Webinar]. YouTube. https://youtu.be/x5lg_BD-hDA

Hess, D., Hunter, J., Ascher, A., & Bishop, T. (2021, September 1). Understanding the Initial Preventive Physical Examination (IPPE), the Annual Well Visit (AWV) and cognitive assessments and care plan services [Webinar]. Novitas Solutions. https://bit.ly/3CLc5Bg

McCartin, L. (2020, March 18). Prioritizing curriculum during emergency remote teaching [Webinar]. University of Northern Colorado, Center for the Enhancement of Teaching & Learning, Teaching, Learning & Assessment. https://digscholarship.unco.edu/tla/37/

Pudewa, A. (2018, July 2). Strategies for winning the college writing game [Webinar]. Institute for Excellence in Writing. https://excellenceinwriting.adobeconnect.com/_a946750274/pfkfwvkpj194/

• An single person,
• Multiple people,
• A group author (an institution or organization), or
• Multiple group authors.
• Look for whomever takes credit or responsibility for the information. 
• If there is no individual or group author associated with the information, move the title into the place of author (before the date).
• the copyright date or
• the date of last update.
• Do not use a copyright date from a website footer as this does not give any indication of when the information was written; if no other date is available, us the rules of no date.
• For journal articles that have been accepted by a journal but not yet published, use the notation (In press). 
• Use circa (abbreviated ca.) for approximate dates, as in (ca. 1930). 
• If there is no date associated with the information, use the notation of n.d., for no date, as in (n.d.).
• entire standalone works (e.g., books, journals, albums, etc.) and
• works that a part of a greater whole (e.g., book chapters, journal articles, songs, etc.).
• For works that are not books, journal/journal articles, magazine/magazine articles, or newspaper/newspaper articles include a description of the type of work directly after the title and before ending punctuation inside square brackets.
• Source information varies by type, format, and retrieval method of source. For example, a print newspaper article has different source information than an online book. See examples on this page and the Publication Manual (pp.293-301).
• Generally a group author, but may be a mix of group and individual authors
• Date of publication
• Title of report
• Report number or designation (sometimes an alphanumeric code)
• Publisher name or organization (if different than the author)
• URL - if an online report

Government Report Online

Centers for Disease Control and Prevention. (2021, April). HIV infection, risk, prevention, and testing behaviors among transgender women (HIV Surveillance Report No. 27). https://bit.ly/3N2xWZJ

Department of Regulatory Agencies & Department of Health Care Policy and Financing. (2019, November 15). Final report for Colorado’s public opinion. State of Colorado. https://bit.ly/37umoOm

Internet Crime Complaint Center. (n.d.). 2020 internet crime report. Federal Bureau of Investigation. https://www.ic3.gov/Media/PDF/AnnualReport/2020_IC3Report.pdf

United States International Trade Commission. (2019, April). U.S.-Mexico-Canada Trade Agreement: Likely impact on the U.S. economy and specific industry sectors (Report 4889 TPA 105-003). https://www.usitc.gov/publications/332/pub4889.pdf

Government Report Print

Colorado Department of Human Services. (1999, March 1). Assessment of community consolidated child care pilot program: Technical report submitted to the Colorado General Assembly .

Harmon, K. R. (1986, February). Telecommunications study for Colorado libraries: Executive summary report. Colorado Department of Education.

United States General Accounting Office. (1991, June). Professional military education at the four intermediate service schools: Report to the Chairman, Panel on Military Education, Committee on the Armed Services, House of Representatives (GAO/NSAID-91-182). Department of Defense.

Visher, M. G., & Hudis, P. M. (1999, October). Aiming high: Strategies to promote high standards in high schools – interim report. New American High Schools; U.S. Department of Education, Office of Vocational and Adult Education.

• Principal investigator
• Year grant begins
• Year grant ends
• Title of grant
• Grant number (if there is one)
• Granting agency
• URL - if grant abstract is online

Berg, M. (Principal Investigator). (2021-2022). Graduate content literacy for diverse learners, EDRD 515 [Grant]. University of Northern Colorado OER Committee. https://bit.ly/3JpO05w

Burns, P. (Principal Investigator). (2021-2025). Influence of fish oil on corpus luteum function (Grant No. 2021-67016-33839) [Grant]. United States Department of Agriculture. https://portal.nifa.usda.gov/web/crisprojectpages/1024909-influence-of-fish-oil-on-corpus-luteum-function.html

Cheung, P. W. (Principal Investigator). (2018-2021). Characterization of novel signaling pathways involved in water balance disorders (Project No. 3K08DK115901-03S1) [Grant]. National Institute of Diabetes and Digestive and Kidney Diseases. https://reporter.nih.gov/project-details/10165964

Mayer, J. (Principal Investigator). (2018-2019). OER awareness and infrastructure building at the University of Northern Colorado [Grant]. Colorado Department of Higher Education. https://highered.colorado.gov/Publications/Reports/Legislative/OER/OER_Report_2019_Final.pdf

Grey literature basically refers to the wealth of information sources that are not published through traditional publishing houses. This basically includes any information source that is not a book, journal, magazine, or newspaper.

Grey Literature includes materials that are generally

• not published commercially and/or
• not generally accessible and
• can include ephemera

According to the Twelfth International Conference on Grey Literature, the definition is as follows:

"Grey literature stands for  manifold document types produced on all levels of government, academics, business and industry in print and electronic formats  that are protected by intellectual property rights, of sufficient quality to be collected and preserved by libraries and institutional repositories, but not controlled by commercial publishers; i.e., where publishing is not the primary activity of the producing body" (for more information see  Towards a Prague Definition of Grey Literature - PDF ).

...paint ings, pamphlets,  patents, patient care sheets, plans,  podcas ts, post cards, posters,  practice guidelines, policies,  PowerPoints , preprints, press release,  Prezis , proceedings...

Determining How to Cite Grey Literature

• Check the Reference Citations on this Guide.
• Consult the Publication Manual 7th Edition .
• Consult the APA Style Blog .
• Investing for life [Brochure] .
• How to create online continuing education classes [Webinar] .
• Anatomical model
• Annual report
• Apparatus and data file
• Blog comment
• Blu-ray disc
• Book review
• CD recording
• Conference presentation
• Committee report
• Computer software
• Database record
• Demographic map
• Electronic mailing list comment
• Facebook page
• Facebook post
• Lecture notes
• Letter to the editor
• Measurement instrument
• Mission statement
• Mobile application software
• Motion picture
• Online forum comment
• Organizational standards
• Physiological specimens
• Podcast transcript
• Policy documents
• Policy statements
• PowerPoint presentation
• PowerPoint slides
• Practice guidelines
• Press release
• Prezi presentation
• Product catalog
• Questionnaire
• Research notes
• Research proposal
• Scientific protocol
• Tape recording
• Television series episode
• Television series webisode
• Topographic map
• Twitter update

Journal Article

with DOI • Print Version  • with URL  • in Library Databases  • with Article Number  • with Page Numbers  • Advance Online Publication  • In Press

• Year of Publication
• Title of Article
• Title of Journal
• Volume Number
• Issue Number
• Page Numbers or Article Number

Journal Articles with DOI

Freeze, J. G., Kelly, H. R., & Batista, V. S. (2019). Search for catalysts by inverse design: Artificial intelligence, mountain climbers, and alchemists. Chemical Reviews, 119 (11), 6595-6612.  https://doi.org/10.1021/acs.chemrev.8b00759

Katada, S. N. (2013). Financial crisis fatigue? Politics behind Japan’s post-global financial crisis economic contractions. Japanese Journal of Political Science, 14 (2), 223-242. https://doi.org/10.1017/S1468109913000042

Parsons, S. (2009). Sontag’s lament: Emotions, ethics, and photography. Photography and Culture, 2 (3), 289-302. https://doi.org/10.2752/175145109X12532077132356

Journal Articles Print Version

Meeker, M. (2001). Behind the mask of respectability: Reconsidering the Mattachine Society and male homophile practice, 1950s and 1960s. Journal of the History of Sexuality, 10 (1), 78-116.

Wechsler, H., Lee, J. E., Kuo, M., & Lee, H. (2000). College binge drinking in the 1990s: A continuing problem – results of the Harvard School of Public Health 1999 college alcohol study. College Health, 48 (5), 199-2010.

Wester, F. R. (1953). A technique for the measurement of race attitudes. American Sociological Review, 18 (1), 73-78.

Journal Articles with URL

Hopsicker, P. M. (2014). Racing to death: The not-so-ordinary happenings of the 1932 Lake Placid Olympic bobsled events. Journal of Sport History, 41 (1), 73-93. https://muse.jhu.edu/article/544501/pdf

Moskalik ,  T.,  Borz , S. A.,  Dvořák , J.,  Ferencik , M.,  Glushkov , S.,  Muiste , P.,  Lazdiņš , A., &  Styranivsky , O.  (2017). Timber harvesting methods in Eastern European countries: A review.  Croatian Journal of Forest Engineering, 38 (2), 231-241. https://bit.ly/376dRgA  

Rashidi, Z., Azadbakht, M., Amini, A., & Karimi, I. (2014). Timber harvesting methods in Eastern European countries: A Review. Cell Journal, 15 (4), 282-293. https://celljournal.org/journal/article/abstract/591

Journal Articles in Library Databases

Journal Articles with Article Number

Cucuzzella, C., Chupin, J.-P., & Hammond, C. (2020). Eco-didacticism in art and architecture: Design as means for raising awareness. Cities, 102 , Article 102728.   https://doi.org/10.1016/j.cities.2020.102728

Rothan, H. A., & Byrareddy, S. N. (2020). The epidemiology and pathogenesis of coronavirus disease (COVID-19) outbreak. Journal of Autoimmunity, 109 , Article 102433. https://doi.org/10.1016/j.jaut.2020.102433

Urada, L. A., Rusakova, M., Odinokova, V., Tsuyuki, K., Raj, A., & Silverman, J. G. (2019). Sexual exploitation as a minor, violence, and HIV/STI risk among women trading sex in St. Petersburg and Orenburg, Russia. International Journal of Environmental Research and Public Health, 16 (22), Article 4343. https://doi.org/10.3390/ijerph16224343

Journal Articles with Page Numbers

Meadwell, J., Paxman-Clarke, L., Terris, D., & Ford, P. (2019). In search of a performing seal: Rethinking the design of tight-fitting respiratory protective equipment facepieces for users with facial hair. Safety and Health at Work, 10 (3), 275-304. https://doi.org/10.1016/j.shaw.2019.05.001

Taddei, C., Zhou, B., Bixby, H., Carrillo-Larco, R. M., Danaei, G., Jackson, R. T., Farzadfar, F., Sophiea, M. K., Di Cesaire, M., Caminia lurilli, M. L., Rodriguez Martinez, A., Ashgari, G., Dhana, K., Gulayin, P., Kakarmath, S., Santero, M., Voortman, Riley, L. M., Cowan, M. J.,…Ezzati, M. (2020). Repositioning of the global epicentre of non-optimal cholesterol. Nature, 582 (7810), 73-77.  https://doi.org/10.1038/s41586-020-2338-1

Zhong, Y.-P., Shen, X.-T., Ying, Y., Wu, H.-T., Li, J., Qi, Q., Zhou, C.-Q., & Zhuang, G.-L. (2012). Impact of transitory hyperprolactinemia on clinical outcome of in vitro fertilization and embryo transfer. Journal of Medical Biochemistry, 31 (1), 27-33. https://doi.org/10.2478/v10011-011-0039-x

Journal Articles, Advance Online Publication

Esposito, E., Li, W., Mandeville, E. T., Park, J.-H., Şencan, I., Guo, S., Shi, J., Lan, J., Hayakawa, K., Sakadžić, S., Ji, X., & Lo, E. H. (2020). Potential circadian effects on translational failure for neuroprotection. Nature. Advance online publication. https://doi.org/10.1038/s41586-020-2348-z

Jose, K., MacDonald, F., Vandenberg, M., Williams, J., Abbott-Chapman, J., Venn, A., & Smith, K. J. (2020). School breakfast club programs in Australian primary schools, not just addressing food insecurity: A qualitative study. Health Education & Behavior. Advance online publication. https://doi-org.unco.idm.oclc.org/10.1177/1090198120920193

Rűber, I. E., & Janmaat, J. G. (2020). Does participation in adult education increase volunteering? An analysis of British longitudinal data. Adult Education Quarterly. Advance online publication. https://doi-org.unco.idm.oclc.org/10.1177/0741713620927348

Journal Articles in Press

In press articles are also called Journal Pre-Proofs.

In press articles are articles are manuscripts that have been submitted to and accepted by a journal, but are still in the process of final production; therefore, it is possible mistakes are included in this version of the article that will be caught and corrected before the final version. It is important to note in citation when working with an in press article, so that the reader knows the version of the article any information came from. Not all journals put in press articles online for others to see. It is generally journals in the sciences that offer access to articles before the final version is completed. In general, in press articles will not have a volume, issue, or page numbers; they may or may not be assigned a DOI.

Magazine Articles

Magazine Article Print Version • Magazine Article from Library Database   • Magazine Article on Open Web

• If no author is listed, move the magazine article title into the place of the author
• Date of publication
• Title of article
• Title of magazine
• Volume, issue, and page numbers are often not available for online magazine articles; if they are not available omit the numbers
• Magazine articles are not always on sequential page numbers; if an article appears non-sequentially give the first page or page range followed by a comma followed by the second page or page range, and so on
• URL - for online magazine articles

Magazine Article Print Version

Malcolm, J. (2018, October 29). Six glimpses of the past: Photography and memory. The New Yorker, 94 (34), 18-26.

Shah, S., & El-Sayed, A. (2022, January). Medical algorithms need better regulations. Scientific American, 326 (1), 10-11.

Spradley, N. (2016, December). Strokes of genius. Essence, 47 (8), 45-46, 48, 50.

What you should know about AirPods. (2022, March). Consumer Reports, 87 (3), 14-15.

Magazine Article in Library Database

Magazine Article on Open Web

Berinato, S. (2022, January-February). When people listen to happy songs, the market outperforms. Harvard Business Review. https://hbr.org/2022/01/when-people-listen-to-happy-songs-the-market-outperforms

Boyes, A., Esposito, L., Gillihan, S., & Leyba, E. (2021, May 4). The high cost of calm. Psychology Today. https://www.psychologytoday.com/intl/articles/202105/the-high-cost-calm

Faber, T. (Author), Lai, A. (Photographer), & Tao, K. (Stylist). (2022, March 15). David Erritzoe: On the mind-bending potential of psychedelics. Kinfold, 43 . https://www.kinfolk.com/david-erritzoe/

Howley, E. K. (2021, June 4). COVID-19 vaccines for children: Timing, side effects and more. U.S. News & World Report. https://health.usnews.com/conditions/coronavirus-and-your-health/articles/covid-19-vaccines-for-children-timing-side-effects-and-more

If citing a new source from a newspaper , magazine , blog , or video site like YouTube , see examples under these types of sources. For news sources on websites such as ABC News, CBS News, CNN, HuffPost, MSNBC, NBC News, NPR, Reuters, Salon, Vox, etc., site as examples given below.

• If there is no author, move the title of the news article before the date element.
• News site name

News Site - Article with Author(s)

Fulcher, M. P. (2022, March 20). Boulder prepares to mark a painful milestone – a year since the King Soopers Shooting . CPR News. https://www.cpr.org/2022/03/20/boulder-prepares-to-mark-a-painful-milestone-a-year-since-the-king-soopers-shooting/

Karanth, S. (2022, March 16). 1 year after Atlanta spa shootings, Asian American women still face hate and violence. HuffPost. https://bit.ly/3qmU8nq

Sneed, T., & de Vogue, A. (2022, March 21). What Ketanji Brown Jackson might be grilled about her Supreme Court confirmation hearings . CNN. https://www.cnn.com/2022/03/21/politics/what-to-expect-ketanji-brown-jackson-confirmation-hearings/index.html

Thrash, R. (2022, March 21). 2 Pennsylvania troopers hit by a car and killed as they helped man on interstate, police say. CBSNews. https://www.nbcnews.com/news/us-news/two-pennsylvania-troopers-three-hit-car-killed-95-rcna20820

Website, Author and Publisher Are Same

Chinese Boeing jet crashes in mountains with 132 on board, no sign of survivors . (2022, March 21). Reuters. https://www.reuters.com/world/china/china-eastern-airlines-passenger-jet-has-accident-guangxi-state-media-says-2022-03-21/

Marine pilot killed in Osprey crash in Norway was a native on Leominster. (2022, March 21). WCVB Boston. https://www.wcvb.com/article/marines-pilot-capt-ross-reynolds-killed-in-norway-osprey-crash-was-a-native-of-leominster/39485562

Newspaper Articles

Newspaper Article Print Version • Newspaper Article from Library Database   • Newspaper Article on Open Web

• Author(s) - if no author is listed, move the newspaper article title into the place of the author
• If citing something without a title (such as an advertisement), write a description of the piece inside square brackets.
• If the title of newspaper lends itself to ambiguity (such as a common title such as The Daily Sentinel) place the city and state of the newspaper in square brackets after the title of the newspaper.
• Page numbers are often not available for online newspaper articles; if they are not available omit them
• Newspaper articles are not always on sequential pages; if an article appears non-sequentially give the first page or page range followed by a comma followed by the second page or page range, and so on
• URL - for online newspaper articles

Newspaper Article Print Version

Coyotes around Nunn numerous and bold. (1916, May 10). Greeley Daily Tribune , 6.

Hindi, S. (2018, May 3). Defense lawyer releases video from body camera. Fort Collins Coloradoan , A1, A3.

Klomhaus, S. (2022, February 10). Assessment finds Mesa County is lacking in available child care. The Daily Sentinel [Grand Junction, Colorado], A3.

[Advertisement for Saks & Company women’s wraps, capes, and coat sale with prices]. (1920, May 11). The New York Times , 5.

Newspaper Article in Library Database

Newspaper Article on Open Web

Carlson, M. (2022, January 2). Betty White obituary. The Guardian . https://www.theguardian.com/tv-and-radio/2022/jan/02/betty-white-obituary

Casanova, S., & Sweeney, A. (2021, July 28). Violence spike of 2020 widened familiar safety gap between city neighborhoods, University of Chicago Crime Lab analysis shows. Chicago Tribune . https://bit.ly/3JmCeso

Dickerson, B. (2022, March 16). Opinion: Zelenskyy is the leader of the free world now. Detroit Free Press . https://bit.ly/3qdVnW1

Kafer, K. (2021, November 17). Denver talk show host is in hot water for false election fraud claims. The Denver Post . https://www.denverpost.com/2021/11/17/randy-corporon-talk-show-host-defamation-lawsuit-dominion-election-fraud/

Personal Communications

Emails • Text Messages   • Private Letters   • Online Chats   • Direct Messages   • Memos   • Telephone Conversations   • Unrecorded Classroom Lectures   • Personal Conference Notes   • Live Speeches  

Personal communications are only cited with an In-Text Citation. Do not give a Reference Citation.

Personal Communications are  unpublished information sources  that are not recoverable by the greater population (readers). For published communications, use the corresponding published format for citation examples ( i.e. , for letters published in a book, cite a book; personal communications may be published in journal articles, books, book chapters, blogs, websites,  et cetera ).

• Name of the person the information came from
• Date of the communication - Month, Day and Year
• If possible, give context within your writing as to the type of source you are citing (compare the Letter example - where context is given - with the Memo Letter, in which no context is given)
• Parenthetical In-Text Citation: (R. J. Rymill, personal communication, January 12, 1936)
• Narrative In-Text  Citation: R. J. Rymill (personal communication, January 12, 1936)

In a letter written by Wyoming State Senator  Robert J. Rymill  ( personal communication, January 12, 1936)  to his brother W. L. Rymill, the senator stated, “Serving on city and county school boards is the most successful avenue to changing education."

• Parenthetical In-Text  Citation: (C. Okafor, personal communication, July 7, 2017)
• Narrative In-Text  Citation: C. Okafor (personal communication, July 7, 2017)

Chief Operating Officer  Cecelia Okafor   ( personal communication, July 7, 2017 )  advised the Board of Trustees of the necessity of managing human capital costs and cross-training efforts .

Conversation (Personal)

• Parenthetical In-Text  Citation: (C. Myers, personal communication, June 10, 2017)
• Narrative In-Text  Citation: C. Myers (personal communication, June 10, 2017)

One presenter, at a recent copyright conference, stated, “My best advice regarding the amount used is to consider the amount needed to serve the purpose in relation to the work being used” ( C. Myers, personal communication, June 10, 2017 ).

Text Message

The following example is for a text message from an unknown source. Generally, the author of a text message is known and both Parenthetical and Narrative In-Text Citations will include the author's name.

• Parenthetical In-Text  Citation: (personal communication, May 27, 2020)

A text message sent from an unknown source ( personal communication, May 27, 2020 ) stated, "Some who came into contact with you tested positive or has shown symptoms for COVID-19 & recommends you self-isolate/get tested." Cable News Network (CNN, 2020) later reported that individuals across the United States received the same or similar text messages that including a link that - if activated - downloaded malware onto the recipient's computer.

• Parenthetical In-Text  Citation: (G. Hampson, personal communication, April 20, 2020)
• Narrative In-Text  Citation: G. Hampson (personal communication, April 20, 2020)

In an email, G. Hampson  ( personal communication, April 20,2020 ) expressed his opinion on commercial (for-profit) entities' involvement in open access as follows:

I think we can build a very effective future on this common ground instead of continuing along the path where we divide our community into those whose motives are “pure,” and those who also look to do this work in a sustainable business manner.

Classroom Lecture (Unrecorded)

• Parenthetical In-Text  Citation: ( S. P. Mackessy , personal communication, January 21, 2020)
• Narrative In-Text  Citation: S. P. Mackessy (personal communication, January 21 , 2020 )

During a session of a human anatomy course at the University of Northern Colorado, Professor S. P. Mackessy  ( personal communication, January 21,2020 ) referenced a forensic investigation in which snake venom was used as a poison in the death of a two-year-old.

A note on keeping a personal Dark Archive for Personal Communications used in research.

The Society of American Archivists defines a Dark Archive as " a repository that stores archival resources for future use but is accessible only to its custodian" or a " collection of materials preserved for future use but with no current access."

Generally, a Dark Archive is not necessary or advisable for student papers; however, for theses, dissertations, and formally published works, a Dark Archive of Personal Communications is recommended. Thus, if you cite an email in a journal article, keep that email so that if anyone asks you about the information in the email or questions the veracity of the information, you still have that information accessible.

Podcast Series

• Years of Podcast Activity - this will generally be a range of years; the beginning year is the year in which the first episode was produced and the last year is the year in which the last year of the podcast was produced; if the podcast is still producing episodes, the latter part of the date range is noted as 'present'
• Title of Podcast
• Type of Podcast - audio or video
• Production Company

DJ Envy, Yee, A., & Charlamagne tha God (Hosts). (2010-present). The breakfast club [Audio podcast]. iHeartRadio. https://www.iheart.com/podcast/the-breakfast-club-24992238/

Rogan, J. (Hosts). (2009-present). The Joe Rogan experience [Video podcast]. Spotify. https://open.spotify.com/show/4rOoJ6Egrf8K2IrywzwOMk

Shepard, D., & Padman, M. (Hosts). (2018-present). Armchair expert with Dax Shepard [Audio podcast]. Simplecast. https://armchairexpertpod.com/

Podcast Episode

• Date of Episode (Year, Month Day)
• Title of Episode
• Type of Podcast
• URL - if the episode is accessed through an app, the URL can be omitted)

Abumrad, J. (Host). (2019, November 19). The only one for me, Jolene [Audio podcast episode]. In Dolly Parton’s America . WNYC Studios. https://www.wnycstudios.org/podcasts/dolly-partons-america/episodes

Eagan, D. (Host). (2021, April 2). Elevators: Terror and death in a 6 by 6 foot box (No. 3) [Audio podcast episode]. In Strange and unexplained . Obsessed Network. https://www.strangeandunexplainedpod.com/post/episode-3-elevator-stories

Ko, C., & Miller, N. (Hosts). (2021, December 9). Matt Damon ruins your Saturday (No. 217) [Video podcast episode]. In Tiny meat game podcast . TMG Studios. https://www.youtube.com/watch?v=-_aUaq1mYds

• If no author is given, move the title of the slide deck to the first element position in the citation.
• If no date is given, use n.d. in place of a date to indicate "no date"
• For various online slide software, it may be necessary to to figure out where this information is located (for example, for Google Slides select File>>Document Details which gives the creation date for the Google slide deck)
• Title of slide deck
• Publisher or host website
• If the slide deck is behind a firewall (e.g., Canvas, Blackboard, a company intranet) and the main audience of the slide deck is within the organization that has access to materials behind the firewall, provide the name of the platform and the URL of the platform sign-on page.
• If the slide deck is behind a firewall and the main audience does NOT have access to materials behind the firewall, cite the slide deck as a personal communication.

Davenport, B. (2015, May 17). 20 stress-free ways to declutter your home [Slides]. SlideShare. https://www.slideshare.net/bbdavenport/20-stressfree-ways-to-declutter-your-home

Denny, M. (2021, April 20). Setting writing goals & staying motivated [Google slides]. Google. https://bit.ly/37Lg05v

Mayer, J., & Webber, N. (2017, November 9). Showcase your impact as an author/creator and tell your research story [PowerPoint slides]. University of Northern Colorado Scholarship & Creative works @ Digital UNC. https://digscholarship.unco.edu/workshops/1/

Wei, L. (n.d.). Multilingualism, social cognition, and creativity [PowerPoint slides]. Stony Brook University. https://www.stonybrook.edu/commcms/mic/_pdf/LiWeiSlides.ppt

Wiegand, S. (2018, Fall). Asking an answerable question, part III [Slides]. University of Northern Colorado Canvas Learning Management System. https://www.unco.edu/canvas/

Yohe, E. (2021, February 25). What you need to know about paid leave law [Slides]. Colorado Department of Labor and Employment. https://cdle.colorado.gov/sites/cdle/files/documents/CLDE_DLSS_Webinar_PresenationDeck_Web.pdf

Research instruments are sometimes referred to as tests. They are scales, inventories, questionnaires, and measurement tools used to collect data.

• Individual(s) and/or Group(s)
• If no year is associated with the instrument, give the notation for no date (n.d.)
• If no title is associated with the instrument, give a description of the instrument in square brackets
• Publisher, if available
• Database name, if citing at database record
• DOI or URL, if available

Manual for Research Instrument

Kerby, M. L. (1980). Kerby learning modality test: Manual (Rev. Ed.). Western Psychological Services.

Messer, B., & Harter, S. (2012). The self-perception profile for adults: Manual and questionnaires. University of Denver, Department of Psychology. https://portfolio.du.edu/downloadItem/225566

Sanders, C. M., Mauger, P. A., & Strong, P. N., Jr. (1984). Grief experience inventory: Manual. Consulting Psychologists Press.

Research Instrument - Test, Scale, Questionnaire

Alliance for the Study of School Climate. (n.d.). School climate assessment instrument (SCAI): Elementary teacher version (Version 2016 7.2.3). California State University-Los Angeles. https://web.calstatela.edu/centers/schoolclimate/pdf/assessment/ASSC-SCAI-E-G.pdf

American Chronic Pain Association. (n.d.). Quality of life scale: A measure of function for people with pain. https://health.gov/hcq/trainings/pathways/assets/pdfs/QOL_scale.pdf

Cohen, S. (n.d.). Perceived stress scale: 10 item . https://www.cmu.edu/dietrich/psychology/stress-immunity-disease-lab/scales/html/pss.html

Mart, E. G. (2011). The practical assessment of testamentary capacity and undue influence in the elderly . Professional Resource Express.

Database Record for Research Instrument

Mind Garden. (1977). Ways of coping questionnaire [Database record]. CINAHL Plus with Full Text. https://www.ebsco.com/products/research-databases/cinahl-plus-full-text

Peterson, J. C. (2016). Stress management questionnaire (Rev. Ed.) [Database record]. Mental Measurements Yearbook with Tests in Print. https://www.ebsco.com/products/research-databases/mental-measurements-yearbook-tests-print

Zeitlin, S, Williamson, G. G., & Szczepanski, M. (n.d.). Early coping inventories: A measure of adaptive behavior, observation and self-rated forms [Database record]. PsycTESTS. https://doi.org/10.1037/t12063-000

Social Media

Facebook   • DeviantArt   •  Instagram • LinkedIn   •  Twitter   • and many more...

Social Media defined by Merriam-Webster Online Dictionary : F orms of electronic communication (such as websites for social networking and microblogging) through which users create online communities to share information, ideas, personal messages, and other content (such as videos).

Social Media defined by Merriam-Webster Online Dictionary : F orms of electronic communication (such as websites for social networking and microblogging) through which users create online communities to share information, ideas, personal messages, and other content (such as videos).

Cite social media information only when it is original information. For example, if a Facebook post links you to an article on the UNICEF website, site only the UNICEF site and not the Facebook post; however, if the Facebook post offers original information, such as a Facebook post by a parent expressing the need for face mask exemptions for students in primary school, this is original information and you cite the Facebook post.

• Author - Real name, screenname, username
• Date - Day, month, and year
• Regular title
• Content of the post up to the first 20 words
• If audiovisuals, give the type of audiovisual in square brackets 
• Site or platform title
• URL - if the content is changing and updating (such as on a wiki) give the retrieval date

For examples of citing YouTube and TikTok videos, see .

Butko, B. [lincoln_highway]. (2020, August 20). A derecho storm with winds up to 140 mph has devastated Iowa, damaging or destroying 13 million acres of crops [Photograph]. Instagram.  https://www.instagram.com/p/CEHq1J_lcCc/

National Portrait Gallery [nationalportraitgallery]. (2022, February 16). Today's #portraitoftheday is none other than Oscar Wilde [Photograph]. Instagram.  https://www.instagram.com/p/CaCn4yjMoPJ/

University of Northern Colorado [unc_colorado]. (2022, February 10). Great careers start in bear country. Yours can too! Network with alumni working in careers you want to pursue [Video].  https://www.instagram.com/p/CZziObQBFy8/

Feinstein, A. (n.d.). Home [LinkedIn page]. Retrieved March 7, 2022, from  https://www.linkedin.com/in/andyfeinstein/

Morse, A. (2022, March 5). It was great having Sara Frederic of Mississippi State University join us in our University of Northern Colorado of sport [Image attached] [Post]. LinkedIn.  https://www.linkedin.com/feed/update/urn:li:activity:6905657650567032832/

University of Northern Colorado. (2021, May 7). UNC track and field student-athlete and new grad Armanni Portee '21 connected with alumnus and former football player Jonathan Martin [Video attached] [Post]. LinkedIn.  https://www.linkedin.com/posts/university-of-northern-colorado_uncbears-alumni-connections-activity-6800803462264303616-QoEh 

Obama, B. [@BarackObama]. (2022, March 3). The Ukrainian people need our help. If you're looking for a way to make a difference, here are some organizations [Thumbnail with link attached] [Tweet]. Twitter.  https://twitter.com/BarackObama/status/1499505056126808068

Musk, E. [@elonmusk]. (n.d.). Tweets [Twitter profile]. Twitter. Retrieved March 8, 2022,  https://twitter.com/elonmusk

Rocky Mountain National Park [@RockyNPS]. (2015, November 17). The next time someone tells you to take a hike, head to #RMNP! #TakeAHikeDay [Image attached] [Tweet].  https://twitter.com/RockyNPS/status/666668053522960384

Woodson, J. [@JackieWoodson]. (2022, March 4). This happened tonight. #HansChristianAndersenMedal 'for the most distinguished contribution to international children's literature' #IBBY2022 [Image attached] [Tweet]. Twitter.  https://twitter.com/JackieWoodson/status/1499994495760449540

Student Work

Action Research Projects  • Capstones • Dissertations   • Master's Theses  • Undergraduate Honors  Theses

Published student work refers to students works that are available online through a commercial database (such as ProQuest Dissertations & Theses Global , through an institutional repository (such as Scholarship & Creative Works @ Digital UNC ), on a personal website, or other source. Unpublished student work refers to student works that are kept by a university but are only available in print.

• Title of work
• Type of work
• Name of institution awarding an associated degree
• If published: name of database, institutional repository, archive, or website
• If published, but not in a commercial database: URL

Action Research Project

Felder, A. (2020). The impact of research workbooks on assessment [Action research project, University of Northern Colorado]. Scholarship & Creative Works @ Digital UNC.  https://digscholarship.unco.edu/arp/25/

Fiumara, D. A. (2016). The effects of motivational strategies to increase teachers' commitment and enthusiasm [Action research project, St. Catherine University]. Sophia, the St. Catherine University Repository.   https://sophia.stkate.edu/maed/136/

Mousel, S. (2006). Bad medicine: Homework or headache? Responsibility and accountability for middle level mathematics students [Action research project, University of Nebraska Lincoln]. DigitalCommons@University of Nebraska-Lincoln.  https://digitalcommons.unl.edu/mathmidactionresearch/51/

Senn, K. (2018). Evidence-based tuberculosis screening and testing clinical protocol for public health and primary care providers [Doctoral capstone, University of Northern Colorado]. Scholarship & Creative Works @ Digital UNC.  https://digscholarship.unco.edu/capstones/38/

Wu, T. (2019). Give me a good reason: Exploring tightness-looseness as a framework for norms-nudges [Master's capstone, University of Pennsylvania]. ScholarlyCommons.  https://repository.upenn.edu/mbds/15/

Doctoral  Dissertation

Beaumont, E. (2004). An empirical study of family group visitors to a millennium art gallery in the UK (Publication No. 2561899289) [Doctoral dissertation, University of Salford]. ProQuest Dissertations & Theses Global.

Becker, D. (2021). From babysitting to teaching - Latina childcare providers acquiring effective teaching strategies: A grounded theory of transformative professional development [Doctoral dissertation, University of Northern Colorado]. Scholarship & Creative Works @ Digital UNC.  https://digscholarship.unco.edu/dissertations/789/

DeFries Gallagher, A. (2021). A qualitative analysis of the recommended implementation and replication of the cure violence model according to New York City and Chicago program staff interviews [Doctoral dissertation, Johns Hopkins University]. JScholarship.  http://jhir.library.jhu.edu/handle/1774.2/66850

Lebsack, R. R. (1976). Identifying facilitative characteristics of major advisers by normative judgment analysis [Unpublished doctoral dissertation]. University of Northern Colorado.

Williams, K. J. (2018). The structure of models of second-order set theories [Doctoral dissertation, City University of New York]. Kameryn J. Williams.  http://kamerynjw.net/research/pubs/diss/kwilliams-diss.pdf

Master's Thesis

Baretta, M. (2021). Exploring communication strategies used by speech-language pathologists and nursing professionals prior to and during the coronavirus disease 2019 pandemic [Master's thesis, University of Northern Colorado].  Scholarship & Creative Works @ Digital UNC.  https://digscholarship.unco.edu/theses/213/

Gallagher, W. J. (1990). The effect of altitude induced hypoxia on visual evoked potentials [Unpublished master's thesis]. University of Northern Colorado.

Han, M. N. (1994). State succession by Ukraine: Territories and armed forces from the former USSR [Master's thesis, Central Michigan University].  ProQuest Dissertations & Theses Global.

Undergraduate Honors Thesis

Ardovino, A. (2013). Heroes of rock: A design post mortem exploring the video game design process as it relates to player satisfaction [Undergraduate honors thesis, University of Utah]. USpace Institutional Repository.  https://collections.lib.utah.edu/ark:/87278/s6611f5q

Brown, S. A. (2021). Understanding how high levels of noise affect the equine auditory system [Undergraduate honors thesis, University of Northern Colorado]. Scholarship & Creative Works @ Digital UNC.  https://digscholarship.unco.edu/honors/48/

Chuor, B. N. (2018). Asian-American political participation: The consequences of social invisibility and political alienation [Senior honors thesis, University of Houston]. University of Houston Institutional Repository.  https://uh-ir.tdl.org/handle/10657/4308

• Title of UpToDate article
• Retrieval date
• change  https:/ /www-uptodate-com .unco.idm.oclc.org /contents/homesickness ?search=homesickness&source=search_result&selectedTitle=1~1&usage_type=default&display_rank=1  
• to  https://www.uptodate.com/contents/homesickness

Chou, R. (2022). Subacute and chronic low back pain: Nonsurgical interventional treatment. UpToDate . Retrieved February 1, 2022, from https://www.uptodate.com/contents/subacute-and-chronic-low-back-pain-nonsurgical-interventional-treatment

Cohen, P. (2022). COVID-19: Outpatient evaluation and management of acute illness in adults. UpToDate . Retrieved March 5, 2022, from https://www.uptodate.com/contents/covid-19-outpatient-evaluation-and-management-of-acute-illness-in-adults

Thurber, C. A., & Walton, E. (2022). Homesickness. UpToDate . Retrieved March 17, 2022, from https://www.uptodate.com/contents/homesickness

Visual Works

Artwork in Museum  • Artwork on Museum Website • Clip Art, Illustration, Stock Image, & Vector Image   • Exhibition  • in Library Databases  • Infographic   • Installation   • Map   • Mixed Media  •   Painting  • Photograph  • Sculpture   • Slides

• If no author is listed, move the title of the work of art into the place of the author (before the date).
• Date of creation, installation, publication
• If citing a work of art without a title, write a description of the piece inside square brackets in place of the title element.
• Type of art/format
• Include building if appropriate
• Generally includes city, state, nation
• If visual work is found in a database, give the database name instead
• If the visual work was viewed in place, do not give a URL
• If the visual work was viewed online (such as through a museum website or through a database) give the URL
• If the visual work was viewed through a proprietary database, give the homepage of the database instead of a direct URL to the work within the database

Artwork in Museum

Birritjama, D. (n.d.). Cat and crow legend [Painting]. Art Gallery of New South Wales, Sydney, Australia.

Escher, M. C. (1935). Hand with reflecting sphere [Lithograph]. Detroit Institute of Arts Museum, Detroit, MI, United States.

Savage, E. (1796). The Washington family [Painting]. National Gallery of Art, Washington, DC, United States.

Kestrel, S. (1989). Spectre of ancient pathways [Sculpture]. Benson Sculpture Garden, Loveland, CO, United States.

Russin, R. (1959). Abraham Lincoln memorial monument [Sculpture]. Summit Rest Area, Interstate 80, WY, United States.

Weimer, D. (2004). Northern vision [Sculpture]. University of Northern Colorado University Center, Greeley, CO, United States.

Artwork on Museum Website

Ducrollay, J. (1744). Snuff box [Object]. The Wallace Collection, London, United Kingdom. https://bit.ly/3iHcxr7

Macalister, M. (1966). Victim [Sculpture]. Auckland Art Gallery Toi o Tāmaki, Auckland, New Zealand. https://www.aucklandartgallery.com/explore-art-and-ideas/artwork/3360/victim

Meucci, A. (ca. 1825). Mrs. Pierre Toussaint [Painting]. New York Historical Society Museum & Library, New York, NY, United States. https://bit.ly/3wq9efG

Vigée Le Brun, L.-É . (1780). La paix ramenant l’abondance [Peace bringing abundance] [Painting]. The Louvre, Paris, France. https://collections.louvre.fr/en/ark:/53355/cl010061985

Artwork in Library Database

Bourke-White, M. (1936). Wind tunnel construction, Fort Peck Dam, Montana [Photograph]. ArtStor. https://www.artstor.org/

Donald Trump – make America hate again . [Political sticker]. (2015-2016). ArtStor. https://www.artstor.org/

Murakami, T., & Louis Vuitton Design House. (2003). Bag (iid-bfl-141508) [Purse]. Bloomsbury Fashion Central. https://www.bloomsburyfashioncentral.com/

Oscar de la Renta. (ca. 1984). Dress (iid-bfl-141595) [Clothing]. Bloomsbury Fashion Central. https://www.bloomsburyfashioncentral.com/

Clip Art, Illustration, Stock Image, & Vector Image

bniique. (2021, June 2]. [Photograph of close-up of eye with reflection of window]. Pixabay. https://pixabay.com/photos/eyes-look-face-eye-cat-girl-5248678/

Boulart, G. (1877). Exocoetus volitans [Illustration]. Wikimedia Commons. https://commons.wikimedia.org/wiki/File:Exocoetus_volitans.jpg

grmarcstock. (n.d.). Diversity skins of black women and men cartoons [Vector image]. Vecteezy. https://www.vecteezy.com/vector-art/1760631-diversity-skins-of-black-women-and-man-cartoons

Prado, L. (2019, October 24). Dancer [Clip art]. The Noun Project. https://thenounproject.com/icon/dancer-3462518/

Crooks, J. (Curator). (2021, September 1-2022, February 21). Fragments of epic memory [Exhibition; Photographs]. Art Gallery of Ontario, Toronto, Ontario, Canada. https://ago.ca/exhibitions/fragments-epic-memory

Mangat, T. H. (Artist). (2021, October 8-2022, April 23). Capturing the moment: Works by Terrie Mangat [Exhibition; Quilts]. International Quilt Museum at the University of Nebraska, Lincoln, NE, United States.

Oliver, V. C. (Curator). (2021, November 5-2022, February 6). The dirty south: Contemporary art, material culture, and the sonic impulse [Exhibition; Mixed media]. Contemporary Arts Museum, Houston, TX, United States.

Infographic

Bernander, P. (n.d.). Social capital and global health: What trusting relationships tell us about the global burden of disease [Infographic]. https://bit.ly/36etoP6

Cash, I. (n.d.). Infographic of infographics [Infographic]. http://www.ivan.cash/infographic-of-infographics/

León, W., Martinez, J. D., Ramos, C., Saab, Z., & Pacific Rubiales Energy. (2013). History of life as we know it [Infographic]. Bēhance. https://www.behance.net/gallery/10901127/History-of-Life

Installation

Beuys, J. (1983-1985). The end of the Twentieth Century [Installation]. Tate Modern, Bankside London, United Kingdom. https://www.tate.org.uk/art/artworks/beuys-the-end-of-the-twentieth-century-t05855

Christo. (2021, September 18-October 3). L’Arc de Triomphe, wrapped [Installation]. L’Arc de Triomphe, Paris, France. https://christojeanneclaude.net/artworks/arc-de-triomphe-wrapped/

Cummins, P., & Piper, T. (2014, July-November). Blood swept lands and seas of red [Installation]. Tower of London, London, United Kingdom.

Kusama, Y. (2013). Infinity mirrored room – the souls of millions of light years [Installation]. The Art Gallery of Ontario, Toronto, Ontario, Canada.

Clark, W., & Lewis, S. (1814). A map of Lewis and Clark’s track, across the western portion of North America from the Mississippi to the Pacific Ocean by order of the executive on the United States [Map]. Wikipedia. https://bit.ly/3iyHwW5

Google Maps. (n.d.). [Terrain map of Pawnee Buttes Trailhead in Colorado]. Retrieved March 24, 2022, https://bit.ly/3Jz1jk2

Humphreys, A. A., & Egloffstein, F. W. (1858). Rio Colorado of the West (No.2) [Map]. Library of Congress Geography and Map Division, Washington, DC, United States.

International Gay & Lesbian Aquatics. (2020, December). Sexual orientation laws in the world: From criminalisation of consensual same-sex sexual acts between adults to protection against discrimination based on sexual orientation [Map]. Retrieved from https://ilga.org/sites/default/files/downloads/ENG_ILGA_World_map_sexual_orientation_laws_dec2020.png

National Geospatial Technical Operations Center. (2022, March 14). US topo 7.5-minute map for Clarkville SE, CO [Map]. United States Geological Survey. https://www.sciencebase.gov/catalog/item/623a7c15d34e915b67cdf824

United States Forest Service. (2020). Winter motor vehicle use map: White River National Forest, Dillon Ranger District, Colorado, effective dates Nov. 23-May 20 [Map]. University of Northern Colorado James A. Michener Library, Greeley, CO, United States.

Mixed Media

Anatsui, E. (2005). Fading cloth [Mixed media artwork]. Saint Louis Art Museum, St. Louis, MO, United States. https://www.slam.org/collection/objects/48425/

Bradford, M. (2007). Helter skelter I [Mixed media artwork]. The Broad, Los Angeles, CA, United States.

Kokin, L. (2003). Approximation #3 [Mixed media artwork]. Boise Art Museum, Boise, ID, United States. http://www.boiseartmuseum.org/exhibition/bam-unpacked-for-kids/

Pindell, H. (1990). Autobiography: Scapegoat [Mixed media artwork]. Garth Greenan Gallery, New York, NY, United States.

Dali, S. (1972). Mae West lips sofa [Furniture]. Museum Boijmans Van Beuningen, Rotterdam, Netherlands. https://www.boijmans.nl/en/collection/artworks/122647/mae-west-lips-sofa

Oscar Heyman Brothers. (1929). Marjorie Merriweather post brooch [Jewelry]. Museum of Fine Arts, Boston, MA, United States. https://bit.ly/3wtwaLe

Tiffany, L. C. (ca. 1910-1920). Hibiscus and parrots [Stained glass window]. The Met, New York, NY, United States.

United States Army. (1912-1923). 115 th cavalry WWI corporal garrison uniform [Clothing]. Military Memorial Museum, Cheyenne, WY, United States.

Boardman, S. A. (2011). President Obama, Denver State Commission [Painting; Portrait]. Colorado State Capitol, Denver, CO, United States.

Duesberry, J. (n.d.). Still life with chintz and books [Painting]. University of Northern Colorado Archives & Special Collections @ Digital UNC, Greeley, CO, United States. https://digarch.unco.edu/islandora/object/cogru:119851

Green, W. O. (n.d.). The search for knowledge [Painting; Triptych]. University of Northern Colorado James A. Michener Library, Greeley, CO, United States. https://www.unco.edu/library/about_us/art.aspx

Silva, A., & Kiess, Z. (2020). In the middle of difficulty lies opportunity  [Painting; Mural]. 9 th Avenue and 7 th Street, Greeley, CO, United States.

Bell, C. M. (ca. 1849-1893). American Indian man with headdress and bear claw necklace and ornaments [Photograph]. Smithsonian National Museum of Natural History, Washington, DC, United States. https://www.si.edu/object/archives/components/sova-naa-photolot-80-ref540

McClure, L. C. (1927). [Photograph of the view of Voorhies Memorial with Christmas decorations, Civic Center, Denver, Colorado]. Western History Collection, Denver Public Library, Denver, CO, United States.

Vavra, R. (n.d.). Portrait of James A. Michener [Photograph]. University of Northern Colorado Archives & Special Collections @ Digital UNC, Greeley, CO, United States. https://digarch.unco.edu/islandora/object/cogru:125648

Woodman, F. (ca. 1975-1978). [Self-portrait in cemetery with camera in front of face] [Photograph]. Museum of Contemporary Art, Denver, CO, United States. https://mcadenver.org/exhibitions/francesca-woodman

Černý, D. (2007). Metalmorphosis [Sculpture]. Whitehall Corporate Center, Charlotte, NC, United States. https://www.whitehallcorporatecenter.com/metalmorphosis

Kim, M. C. (1998). Sugar Land quan âm [Sculpture]. Vietnamese Buddhist Center, Sugar Land, TX, United States.

Lundeen, G. (1993). The promise of the prairie [Sculpture]. Lincoln Park, Greeley, CO, United States.

Shippen, G. (2016). Sentinel of the Plains [Sculpture]. Brinton Museum, Big Horn, WY, United States. https://thebrintonmuseum.org/collections/sculptures/

When Websites Are NOT Websites When citing the digital version of another type of source, cite it not as a website but as the specific type of source. For example, a digital journal article should be cited as journal article, not a website; a YouTube video should be cited as a video, not a website. This is true for books, book chapters, newspaper articles, magazine articles, dissertations, theses, capstones, grants, podcast, government reports, etc. For more information, refer to the Publication Manual , p. 282, 9.2. 

• Author(s) (group(s), individual(s), or a combination)
• Make sure that the date for the citation refers to the date of the specific content.
• Do not use a copyright date from a website footer as is does not reflect the date the information was created/published. If the copyright date in the website footer is the only data on the website, use n.d. in place of a date to indicate 'no date.'
• Title 
• Include a retrieval date only if the website has information that is designed to change over time

Website, Author and Publisher Are Different

Central Intelligence Agency. (2022, March 3). Bolivia . The World Factbook. https://www.cia.gov/the-world-factbook/countries/bolivia

Mullis, K. (n.d.). Altermune: Chemically programmable immunity . Dr. Kary Banks Mullis 1944-2019. http://www.karymullis.com/altermune.shtml  

National Institutes of Health, National Library of Medicine. (2022, January 15). Famotidine . MedlinePlus. Retrieved March 17, 2022, from https://medlineplus.gov/druginfo/meds/a687011.html

Murray, J. (2021, July 29). What are goji berries? The Spruce Eats. https://www.thespruceeats.com/what-are-goji-berries-3376443

American Red Cross. (n.d.). Building safer communities: Preparing families for disasters around the globe . https://www.redcross.org/about-us/our-work/international-services/building-safer-communities.html

Life Is Good. (n.d.). One van two brothers three simple words: Life is good . https://www.lifeisgood.com/company/about.html

The King Center. (n.d.). The King philosophy – Nonviolence365 . https://thekingcenter.org/about-tkc/the-king-philosophy/

University of Northern Colorado. (2022, January 20). Office of the president: About President Feinstein. https://www.unco.edu/president/about.aspx

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Home / Guides / Citation Guides / Harvard Referencing / Harvard Referencing Style Examples / How to reference an article in Harvard referencing style

How to reference an article in Harvard referencing style

What is an article.

Almost all writers and academics reference other people’s writing in their works. Referencing demonstrates that you have researched your topic, are well versed in its arguments and theories, and it also helps avoid charges of plagiarism.  

The Harvard citation system is just one of many referencing styles – and which style you choose is normally guided by the institution or publication you are writing for.

In this article, you will learn how to use the Harvard citation system to reference the following types of articles:

• journal article
• newspaper article
• magazine article

Properly citing article details in the reference list will help the readers to locate your source material if they wish to read more about a particular area or topic.

Information you need:

• Author name
• (Year published)  
• ‘Article title’  
• Journal/newspaper/magazine name  
• Day and month published, if available
• Volume number, if available
• (Issue) number, if available
• Page number(s), if available

If accessed online:

• Available at: URL or DOI  
• (Accessed: date).

Journal articles

Academic or scholarly journals are periodical publications about a specific discipline. No matter what your field is, if you are writing an academic paper, you will inevitably have to cite a journal article in your research. Journal articles often have multiple authors, so make sure you know when to use et al. in Harvard style . The method for referencing a journal article in the reference list is as follows:

Reference list (print) structure:

Last name, F. (Year published) ‘Article title’, Journal name , Volume(Issue), Page(s).

Shepherd, V. (2020) ‘An exploration around peer support for secondary pupils in Scotland with experience of self-harm’, Educational Psychology in Practice, 36(3), pp. 297-312.

Note that the article title uses sentence case. However, the title of the journal uses title case. Additionally, the volume number comes immediately after the journal title followed by the issue number in round brackets.

If the original material you are referencing was accessed online, then the method for citing it in the reference list will be the same as that in print, but with an additional line at the end.  

Reference list (online) structure:

Last name, F. (Year published) ‘Article title’, Journal Name , Volume(Issue), Page(s). Available at: URL or DOI (Accessed: date).  

Shepherd, V. (2020) ‘An exploration around peer support for secondary pupils in Scotland with experience of self-harm’, Educational Psychology in Practice, 36(3), pp. 297-312. Available at: https://www.tandfonline.com/doi/full/10.1080/02667363.2020.1772726 (Accessed: 08 October 2020).

In-text citation (print or online) structure:

In-text citations are written within round brackets and start with the last name of the author followed by the year published, both separated by a comma.

You can also mention the author within the text and only include the publication year in round brackets.

Examples:  

In this article (Shepherd, 2020) deals with…  

According to Shepherd (2020), when peer support is available…  

Talking about the secondary education system, Shepherd (2020, p.299) suggests that…

Newspaper articles

Even if you are referring to an incident which is public knowledge, you still need to cite the source.  

The name of the author in a newspaper article is referred to as a byline. Below are examples for citing an article both with and without a byline.  

Reference list (print) structure:  

Last name, F. (Year published). ‘Article title’, Newspaper name , Day Month, Page(s).

Hamilton, J. (2018). ‘Massive fire at local department store’, The Daily Local, 10 August, p. 1.

Last name, F. (Year published). ‘Article title’, Newspaper name , Day Month, Page(s). Available at: URL (Accessed: Day Month Year).

Gambino, L. (2020) ‘Kamala Harris and Mike Pence clash over coronavirus response in vice-presidential debate,’ The Guardian, 8 October. Available at: https://www.theguardian.com/us-news/2020/oct/07/debate-kamala-harris-mike-pence-latest-news (Accessed: 8 October 2020).

Reference list structure, no byline:

The basic reference list structure for the reference is the same for both print and online articles. If information isn’t available, simply omit it from the reference.

Newspaper name (Year published) ‘Article Title’, Day Month, Page(s). Available at: URL (Accessed: Day Month Year).

The Chronicler (2016) ‘Local man wins lottery jackpot twice in one year’, 30 May, p. 14. Available at: https://thechroniclerpaper.com/local-man-wins-lottery-twice (Accessed: 1 October 2020).

In-text citation structure (print or online):

The last name of the author and date are written in round brackets, separated by a comma. The method is similar to referencing journal articles in in-text citations.

(Hamilton, 2018)

In his paper, Gambino (2020) mentioned that…

For articles accessed online which do not have an author, the name of the publication is mentioned in place of the author’s name and is italicized.

( The Chronicler , 2016)

Magazine articles  

The structure of magazine articles is similar to that of a journal article.

Last name, F. (Year published) ‘Article title’, Magazine Name , Volume(Issue), Page(s).

Ornes, S. (2020). “To save Appalachia’s endangered mussels, scientists hatched a bold plan”, ScienceNews, (198), p.2.

Last name, F. (Year published) ‘Article title’, Magazine name , Volume(Issue), Page(s). Available at: URL (Accessed: Date).

Ornes, S. (2020) ‘To save Appalachia’s endangered mussels, scientists hatched a bold plan’, ScienceNews, (198), p.2. Available at: https://www.sciencenews.org/article/endangered-mussels-appalachia-rivers-biologists-conservation-plan (Accessed: 3 October 2020).

  In-text citation (print or online) structure:

(Author last name, Year published)

(Ornes, 2020)

Published October 29, 2020.

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References: How to Cite and List Correctly

• First Online: 25 February 2021

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• C. George Thomas 2  

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When we write an essay, research paper, thesis, or book, it is normal to include information from the work of others or support our arguments by reference to other published works. All such academic documents draw heavily on the ideas and findings of previous and current researchers available through various sources such as books, journals, theses, newspapers, magazines, government reports, or Internet sources. In all these cases, proper referencing is essential in order to ensure easy retrieval of information. Referencing is the name given to the method of showing and acknowledging the sources from which the author has obtained ideas or information.

Everything deep is also simple and can be reproduced simply as long as its reference to the whole truth is maintained. But what matters is not what is witty but what is true. Albert Schweitzer (1875–1965)

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Neville, C. 2010. The Complete Guide to Referencing and Avoiding Plagiarism (2 nd Ed.). McGraw-Hill Education, 288 p.

Renu, S. and Thomas, C.G. 2000. Stale seedbed technique for the management of Sacciolepis interrupta in semi-dry rice. Indian J. Weed Sci. 32(3&4):146-149

Rubens, P. 2004. Science and Technical writing: A Manual of Style (2 nd Ed.). Routledge, New York, 427p.

Sheng, T.C. 1989. Soil Conservation for Small Farmers in the Humid Tropics. FAO Soils Bulletin No. 60. Food and Agriculture Organization of the United Nations, Rome, 104p

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The art of referencing: Well begun is half done!

Department of Pediatrics, College of Medicine and Health Sciences, National University of Science and Technology, Sohar, Sultanate of Oman

Department of Pediatrics, Seth G.S. Medical College and K.E.M. Hospital, Mumbai, Maharashtra, India

Introduction

The value of scientific research lies in its wide visibility and access/availability to others; this is generally achieved by a scientific publication as an original (research) paper. The scientific inquiry typically advances based on previously laid ideas/research, making it essential to acknowledge the contribution of the previous authors. The references list is a catalog of literature sources chosen by the researcher to represent the most relevant documents pertaining to his/her study.[ 1 ] The British Standards Institution defines reference as “a set of data describing a document, sufficiently precise and detailed to identify it and enable it to be located.” [ 2 ] References lay the foundation of the paper, providing context for the hypothesis, methodology, interpretation, and justification of the study.[ 3 ] Using other's ideas/thoughts without due credit amounts to plagiarism, compromising the academic integrity of research. A well-referenced paper is thus accurate and complete, adds value and credibility to both the researcher and the source author, and enhances the scientific prestige of the chosen journal.[ 3 ] A bibliography also lists the sources used during research. However, while references only include those sources (journals, books, web information, etc.) which are actually cited in the publication, bibliography comprises all accessed sources (works consulted), irrespective of whether they are cited in the study publication or not.[ 4 ] Thus, referencing in academic writing is an important research tool to display as well as integrate knowledge on a particular subject or topic.[ 5 ]

Importance of Proper Referencing

Scientific research is usually developed on previously established ideas/scientific knowledge. A meticulous literature review at the beginning of the study enables the researcher to identify the work done in the field, identify the gaps in knowledge, and recognize the need for further research.[ 6 ] The most relevant sources from this literature search (essentially) form the list of references. Use of proper referencing is thus beneficial in many ways, such as the following:

• a) It helps the readers to identify and locate the sources used in the research and provides evidence to verify the need/rationale of the study, methodology, inferences, and implications of the study.[ 3 ]
• b) It provides an overview of the techniques/tools used, supports/convinces the reader about the appropriateness of the methodology, and offers a proper perspective in which the research findings need to be interpreted.[ 3 , 7 ]
• c) It is a proof of the author's in-depth reading and knowledge on the subject pertaining to his/her research. References not only highlight similarities in research, but also differentiate the author's ideas from his sources, indirectly acknowledging the author's own contribution to that topic.[ 4 ]
• d) References chosen by a researcher not only credit the individual author/s whose work is cited, but also demonstrate his/her appreciation toward cited authors, at times leading readers toward hitherto lesser-known/unknown author's research.[ 4 , 8 ] By providing acknowledgment to the cited idea/thought, the author also avoids being accused of plagiarism and adds credibility to his/her own work.[ 4 ]
• e) Referenced works steer the readers toward literature pertaining to a particular topic, thus advancing the readers’ interest.[ 4 ] It also allows to trace the origins of ideas and integrates newer ideas (from current research) with previous ones, thus building a web of learning about the topic of interest.[ 9 ]
• f) The reference list provides a list of experts in a specific field, thus helping editors to identify appropriate reviewers.[ 3 ]
• g) It provides peer reviewers with related sources of information to evaluate the manuscript with respect to the cited work.[ 6 ]

Organizing the References

An initial extensive literature search helps in identifying the appropriate research question, drafting the study protocol, supervising ongoing research, analyzing the results, and writing the paper.[ 3 , 7 ] Although references are displayed at the end of the article/after the text of the article, they should not be actually written after completing the text of the manuscript. While drafting the text of the manuscript, the author/s should type the references on a separate MS Word document simultaneously. This preparation allows the writer to choose adequate number of relevant and rational references, avoid bias in his/her research/writing, and limit the reference number as per the target journal for publication.[ 7 ] While citing, it is imperative not to cite broadly, but to do so with respect to the content of the article. Articles which define the topic, lay down background information regarding the study question, give current knowledge about the research, and describe previous studies on a similar study question should be mentioned in the “Introduction” section of the manuscript.[ 10 ] These studies enable to identify existing knowledge, gaps in knowledge, and justify the rationale of the study.[ 6 ] Studies which identify or refer to the method, protocols, or standards (whether new or previously published), elaborate on complex or lesser-known statistical analysis, describe diagnostic criteria, rationalize sample size estimation, or justify use of specific study design/method are best suited as references to the “Methods” section of the manuscript – they help to plan a strong and supported methodology and describe the technique and criteria of the study group.[ 3 , 10 ] Research that reflects on the study findings/results or provides supportive explanation merit mention in the “Discussion” section of the manuscript – they provide information to interpret the study based on existing published data, compare results with those of other studies, and rationalize the implications of the results.[ 10 ]

Though citation analysis treats all references equally, it is important to weigh references in terms of their value to the paper.[ 11 ] While some references are worthy to be mentioned only once in the paper, some are very relevant to the study question and referred to on multiple occasions, and it is important to re-cite only the most relevant articles.[ 3 ] Referencing is not just about stating the publication source (providing relatedness), but also adds value to the paper in terms of representation on the subject and connectivity between knowledge sources (capture the “aboutness”).[ 11 ] References can be books (author/s), legal documents, journal articles, newspaper articles, reports (e.g., official reports from government departments), university working papers, papers presented at conferences, internet sources (including weblogs – blogs and email correspondence), DVD/CD databases, radio/television/videos/audio cassette/CD-ROMs, interview transcripts, and illustrations.[ 12 ]

Choosing Appropriate References

As a rule, whenever one uses an idea, data, diagrams, tables, concepts, methods from a previously published work, it should be cited.[ 12 ] With availability of multiple search engines and abundance of online resources, the task of filtering references may seem daunting.[ 5 ] While choosing references, one should ensure that the original source is completely read and correctly interpreted before its citing.[ 6 ] It is preferable to provide direct references to original article sources as far as possible, choosing a landmark article on the topic.[ 5 ] The choice of references should serve as the most relevant, appropriate, and valuable addition, and one should stick to the most pertinent references that actively support/contradict their conclusions or experience.[ 6 ] It is preferable to use the most recent relevant resources to provide the latest and up-to-date information; however, certain landmark papers may also be cited (even if they are old). Note that very old references may not be available/accessible to reviewers as well as readers.[ 7 ] Often, there are multiple sources for the same information; always prefer references that provide the highest level of evidence (such as meta-analysis), most recent publications, or trustworthy sources such as reputed peer-reviewed journals (with higher impact factor), open access and preferably indexed on reputed databases such as MEDLINE and PubMed.[ 13 , 14 ] Citing works from the journal one wishes to submit demonstrates that author follows that particular journal's publications and values it; however, one should refrain from unethical practices such as coercive citation (when authors are coerced/directed to add irrelevant citations from the editor's journals) or padded citation (when authors pad their reference list with superfluous citations).[ 14 , 15 , 16 ] There should be a judicious combination of original as well as review articles. Review articles summarize a large body of literature and reduce the number of references; however they may be biased and may not reflect the original article accurately.[ 16 ] One should stick to the journal guidelines rigorously (in terms of style and number) to avoid rejection or delay in the processing of the manuscript.[ 6 ] Avoid citing conference abstracts as far as possible, as they provide incomplete or limited information on the subject and often lack an appropriate peer review.[ 16 ] Other sources which lack traditional review and thus may cite inappropriate, unchecked, or promotional content include online sources, such as audio and video presentations, and should therefore be used with caution.[ 17 ] It is also prudent to avoid personal communications and limit their use to situations where essential information is unavailable from a public source (if permission is necessary, then name and date of the communication should be cited in brackets in text).[ 16 ] Limit self-citations to the bare crucial ones that are necessary.[ 18 ] Articles accepted but awaiting publications should be cited as “in press.”[ 16 ] Articles submitted but not yet published should be referenced as “unpublished observations” with written permission from the source; however, since they have not undergone a peer review, they should be (preferably) avoided.[ 16 ] It is prudent to avoid citing articles published in predatory journals.[ 16 ]

There is no need to provide references to facts that are expected to be well known to the journal readers, including historical overviews, own experiences, while outlining previously referenced ideas in conclusions, or while summarizing what is regarded as “common knowledge.”[ 12 ] One should be careful with online sources. There may be errors while copying the uniform resource locator (URL) or the webpage, or the website may change or be closed/inaccessible; hence, cite them only if very essential and check for their reliability and give the date of access.[ 3 ] It is preferable to use online sources with digital object identifiers (DOIs), assuring their permanent presence.[ 13 ] Also, before submission, it is worthwhile to check the US National Library of Medicine's (NLM's) PubMed database ( http://www.pubmed.org ) for any recently published articles related to the manuscript's topic.[ 19 ]

The number of references is determined by the target journal requirements as well as the type of manuscript submitted; for example, the Journal of Postgraduate Medicine allows about 30 references for original articles, up to 15 references for brief reports/grand rounds/clinicopathological forum, 12 references for case series, up to 10 references for case reports/research letter, and five references for a letter to editor ( https://www.jpgmonline.com/contributors.asp#Ref ).

Preparing the References

Citation consists of two components – the “in-text citation” and the “reference list.”[ 7 ] In the in-text citation, quotation marks are used to cite an exact line/phrase from another source, specifically for definitions, examples, or explanations provided by another/earlier author/s.[ 13 ] To prevent plagiarism, it is suitable to interpret and then summarize the cited content in one's own words, referencing the source at the end of the sentence.[ 14 ]

The parts and order in the citation depend on the source which the author is referencing (journal, book, book chapter, or web source) and the journal guidelines. It is imperative to go through the target journal rules and follow the “Instructions to Authors” related to referencing guidelines (the style, punctuation, italics, abbreviations, issue number, volume number, and pages). All the references are generally cited and numbered as per the order in which they are mentioned in the text (and are to be inserted immediately after the source information and not necessarily at the end of the sentence, especially when multiple facts are stated in a single sentence).[ 6 ] In case of a table or a figure, the citation number should be in sequence to that of the preceding text.[ 7 ] The same reference number in which the source is first cited should be used throughout the manuscript (if cited again) as well as in the reference list.[ 7 ] The citation numbers are placed as superscript/in parentheses as per the journal guidelines.[ 7 ] In case of multiple citations, place them immediately after the fact; they should be placed in order of their chronology of publication (or alphabetically if published in the same year) separated by commas.[ 6 , 7 ] If many references are cited consecutively, the numbers can be separated by a hyphen.[ 7 ]

Any documented knowledge (text, audio, or visual) can serve as a source of reference. They can be print based or electronic and include journals, books, doctoral theses, conference papers, newspapers and magazines, web pages, and so on.[ 4 ]

The basic elements while referencing are as follows:[ 13 , 20 ]

• Journal/research paper: Name of author/s, title of paper, journal title (often abbreviated according to the style used for MEDLINE [ www.ncbi.nlm.nih.gov/nlmcatalog/journals ]),[ 16 ] publication year, volume number, issue number (issue number is kept optional by many journals), and page numbers (starting and ending page numbers or e-article number if the journal does not allot page numbers but allots e-article numbers only)[ 13 ]
• Book/chapter: Chapter author/s, title of chapter, editor/s, name of book, edition, publisher, city of publication, year of publication, and page numbers[ 13 ]
• Web sources: Names of author/s, title of webpage, year, weblink, date of access, and other information such as publisher, year of publication, and date of recent update (as may be applicable/available).[ 13 ] When citing a webpage, provide the DOI or URL of the original source as far as possible.[ 1 , 20 ]

Special attention needs to be paid to the punctuations while composing the reference, and the authors must adhere to the style recommended by the journal (that the manuscript will be eventually submitted to). Note that with each revision that the author makes in the manuscript, there may be changes in the order, addition, or deletion of references, and these adjustments should be meticulously ensured to avoid referencing errors.[ 3 ] It is also the author's responsibility to ensure that every citation has a corresponding reference and every reference is cited in the right place and context in the manuscript.[ 6 ] To avoid citation errors, the authors must verify each reference against an electronic bibliographic source like PubMed or print/pdf copies of original resources.[ 16 ] Authors should also verify that none of the cited references is a retracted article; this can be done via MEDLINE by searching PubMed for “Retracted publication [publication type]” or by going directly to the PubMed's list of retracted publications ( https://www.ncbi.nlm.nih.gov/pubmed/?termretractedpublication[publication type] ).[ 16 ]

“Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals” issued by the International Committee of Medical Journal Editors (ICMJE) provides specific information on how to cite sources, which should be followed.[ 16 ] These recommendations by the ICMJE summarize and provide regular updates on how to cite various sources (print documents; unpublished material; audio and visual media; material on CD-ROM, DVD, or disk; and material on the Internet) via Sample References ( www.nlm.nih.gov/bsd/uniform_requirements.html ) on their webpage.[ 16 ] Detailed information is also available in the NLM's Citing Medicine, 2 nd edition ( www.ncbi.nlm.nih.gov/books/NBK7256/ ).[ 20 ] Number of references to be cited should be in accordance with/within the limits as stated in the “Author Guidelines” issued by the target journal.[ 7 ] Authors should take precaution, so as to avoid citing the same reference twice in the list of references.

Types of Referencing Formats/Styles

“Citation style” is the standard format in which the source is documented in the text as well as in the reference list at the end of the manuscript.[ 4 ] In-text citation styles can be broadly classified into numerical referencing style (Numeric style/Vancouver/Institute of Electrical and Electronic Engineers [IEEE] and Running notes style/Modern Humanities Research Association [MHRA]) and name referencing style (Author Date/Harvard, American Psychological Association [APA] and Modern Languages Association [MLA]).[ 12 ] The two major used citation styles are the Vancouver and the Harvard styles, and most other styles are minor modifications of these two styles.[ 4 ] The common citation styles and their examples are summarized in Table 1 .[ 3 , 12 , 13 , 16 , 20 ] Thus, there is a wide variability in the citation style in text as well as reference list; however, the author does not have a choice, but to stick to the style recommended by the journal to which he/she wishes to submit his/her research.[ 3 ]

Citation styles with examples[ 3 , 12 , 13 , 16 , 20 ]

Common Errors in Referencing

Referencing is a tedious task and if not taken seriously and performed diligently, it is prone to many (easily avoidable) errors.[ 7 ] A reference should be accurate, clear, and consistent throughout the manuscript.[ 6 ] An incorrect reference not only questions the credibility of the paper, but also makes it difficult for the reviewers and the readers to seek the cited article, thus denying the source author of due credit for his/her work.[ 3 ] It is the author's responsibility to cite the most relevant and appropriate references in his/her research.[ 3 ] The author should not only locate, read, and understand all sources cited by him/her ( intellectual pleasure ), but also confirm the source and provide all elements of the source correctly ( accuracy ).[ 6 ] The author should be careful not to copy references from an earlier article, but should actually rewrite each selected reference afresh.[ 6 ] Some common errors occurring during referencing are summarized in Table 2 .[ 6 , 7 ]

Common errors in the “in-text citation” and the “reference list”[ 6 , 7 ]

Reference Management Software

As described earlier, there is a wide variation in the journal formatting styles and it is laborious for the researcher to store, organize, and manage the references throughout the process of literature review and protocol planning till the drafting and manuscript submission.[ 21 ] Even more challenging is the addition/deletion or reordering of references (in text as well as in the reference list) with each revision or submission to a newer journal.[ 22 ] There is an increased likelihood of making errors in citing, especially while organizing the references and writing the reference list.[ 23 ] To minimize such errors, reference management software (RMS), also known as citation management software or bibliographic management software, are available to the authors/researchers.[ 21 ] They not only help to search and retrieve the online scientific sources, but also help to import them to their database for storing, organization, and subsequent retrieval.[ 22 ] Many RMS have cloud-based storage, enabling users to be able to access the information from multiple devices as well as collaborate with other researchers.[ 22 ] RMS also allow authors to retrieve citations while writing in the format of desired journal, thus permitting to “cite while you write.”[ 14 ] They also enable addition, deletion, insertion of references in the text and automatic (auto) resequencing of their order in the main manuscript (text) as well as in the reference list.[ 22 ] They can generate reference lists in multiple formats/citation styles to suit the target journal requirements and allow conversion of one format style to another with ease at the click of the mouse.[ 14 ] By linking each citation with a full reference, they ensure each citation in the text is accounted for by a corresponding full reference in the list.[ 12 ] Most of them are compatible for use with common programs such as Microsoft Word and Google Docs.[ 24 ]

There are numerous programs for reference management available in the market – independent applications, those operating within an internet interface, and combination of both these modes.[ 1 ] The most commonly used are Mendeley by Elsevier ( www.mendeley.com ), EndNote ( www.endnote.com ) by Thomson Reuters, and Zotero ( www.zotero.org ).[ 1 ] Some others are RefWorks, F1000 Workspace, JabRef, Citavi, Bibsonomy, ReadCube Papers, Colwiz, Sente, RefME, Connotea, CiteULike, BibTeX, and Microsoft Word.[ 22 , 24 , 25 ] While many of them are free, some are fee based and require a (paid) subscription.[ 13 ]

Despite the use of RMS, one cannot guarantee absence of referencing errors, as there can be errors in details (author names, journal title, dates) or duplication of references when retrieved from different databases.[ 23 ] So, ultimately, the authors (themselves) are responsible for the accuracy of the references cited by them (whether they do the referencing using RMS or manually).

Thus, referencing is an essential part of research and should be assigned due importance, right from the conception of the study question till its delivery as a publication. It plays a vital role throughout the manuscript and appears in almost all sections – from laying down the foundation for study rationale (in the “Introduction” section of the manuscript), describing/justifying the study procedure/s (in the “Methods” section), validating the results (in the “Results” section) and its implications (in the “Discussion” section of the manuscript). References are also utilized by editors to identify subject experts for peer review, by readers to obtain more resources on the subject matter, and by peer reviewers to critically evaluate the manuscript in the light of the available evidence. It is thus essential that references are chosen wisely and carefully as they are representative of the study. It is the author's responsibility to confirm the clarity, accuracy, and appropriateness of the cited sources. One should be careful to avoid common referencing errors to prevent delay/rejection by the journal of interest. As Vancouver style is the commonly preferred citation style by journals of medicine and health sciences, researchers should be well versed with it. Authors should diligently stick to the instructions and style of the target journal. The availability of reference management software such as Mendeley and EndNote has made the authors’ task of collecting, storing, organizing, retrieving, and utilizing the references more efficient and easier; however, it is still the authors’ responsibility to select appropriate references and cite them accurately and correctly.

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Denny, H., Nordlof, J., & Salem, L. (2018). "Tell me exactly what it was that I was doing that was so bad": Understanding the needs and expectations of working-class students in writing centers. Writing Center Journal , 37 (1), 67 – 98. https://www.jstor.org/stable/26537363

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Baumeister, R. F. (1993). Exposing the self-knowledge myth [Review of the book  The self-knower: A hero under control , by R. A. Wicklund & M. Eckert].  Contemporary Psychology , 38 (5), 466–467.

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Speaking, writing and reading are integral to everyday life, where language is the primary tool for expression and communication. Studying how people use language – what words and phrases they unconsciously choose and combine – can help us better understand ourselves and why we behave the way we do.

Linguistics scholars seek to determine what is unique and universal about the language we use, how it is acquired and the ways it changes over time. They consider language as a cultural, social and psychological phenomenon.

“Understanding why and how languages differ tells about the range of what is human,” said Dan Jurafsky , the Jackson Eli Reynolds Professor in Humanities and chair of the Department of Linguistics in the School of Humanities and Sciences at Stanford . “Discovering what’s universal about languages can help us understand the core of our humanity.”

The stories below represent some of the ways linguists have investigated many aspects of language, including its semantics and syntax, phonetics and phonology, and its social, psychological and computational aspects.

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Stanford linguists and psychologists study how language is interpreted by people. Even the slightest differences in language use can correspond with biased beliefs of the speakers, according to research.

One study showed that a relatively harmless sentence, such as “girls are as good as boys at math,” can subtly perpetuate sexist stereotypes. Because of the statement’s grammatical structure, it implies that being good at math is more common or natural for boys than girls, the researchers said.

Language can play a big role in how we and others perceive the world, and linguists work to discover what words and phrases can influence us, unknowingly.

How well-meaning statements can spread stereotypes unintentionally

New Stanford research shows that sentences that frame one gender as the standard for the other can unintentionally perpetuate biases.

Algorithms reveal changes in stereotypes

New Stanford research shows that, over the past century, linguistic changes in gender and ethnic stereotypes correlated with major social movements and demographic changes in the U.S. Census data.

Exploring what an interruption is in conversation

Stanford doctoral candidate Katherine Hilton found that people perceive interruptions in conversation differently, and those perceptions differ depending on the listener’s own conversational style as well as gender.

Cops speak less respectfully to black community members

Professors Jennifer Eberhardt and Dan Jurafsky, along with other Stanford researchers, detected racial disparities in police officers’ speech after analyzing more than 100 hours of body camera footage from Oakland Police.

How other languages inform our own

People speak roughly 7,000 languages worldwide. Although there is a lot in common among languages, each one is unique, both in its structure and in the way it reflects the culture of the people who speak it.

Jurafsky said it’s important to study languages other than our own and how they develop over time because it can help scholars understand what lies at the foundation of humans’ unique way of communicating with one another.

“All this research can help us discover what it means to be human,” Jurafsky said.

Stanford PhD student documents indigenous language of Papua New Guinea

Fifth-year PhD student Kate Lindsey recently returned to the United States after a year of documenting an obscure language indigenous to the South Pacific nation.

Students explore Esperanto across Europe

In a research project spanning eight countries, two Stanford students search for Esperanto, a constructed language, against the backdrop of European populism.

Chris Manning: How computers are learning to understand language​

A computer scientist discusses the evolution of computational linguistics and where it’s headed next.

Stanford research explores novel perspectives on the evolution of Spanish

Using digital tools and literature to explore the evolution of the Spanish language, Stanford researcher Cuauhtémoc García-García reveals a new historical perspective on linguistic changes in Latin America and Spain.

Language as a lens into behavior

Linguists analyze how certain speech patterns correspond to particular behaviors, including how language can impact people’s buying decisions or influence their social media use.

For example, in one research paper, a group of Stanford researchers examined the differences in how Republicans and Democrats express themselves online to better understand how a polarization of beliefs can occur on social media.

“We live in a very polarized time,” Jurafsky said. “Understanding what different groups of people say and why is the first step in determining how we can help bring people together.”

Analyzing the tweets of Republicans and Democrats

New research by Dora Demszky and colleagues examined how Republicans and Democrats express themselves online in an attempt to understand how polarization of beliefs occurs on social media.

Examining bilingual behavior of children at Texas preschool

A Stanford senior studied a group of bilingual children at a Spanish immersion preschool in Texas to understand how they distinguished between their two languages.

Predicting sales of online products from advertising language

Stanford linguist Dan Jurafsky and colleagues have found that products in Japan sell better if their advertising includes polite language and words that invoke cultural traditions or authority.

Language can help the elderly cope with the challenges of aging, says Stanford professor

By examining conversations of elderly Japanese women, linguist Yoshiko Matsumoto uncovers language techniques that help people move past traumatic events and regain a sense of normalcy.

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• 09 May 2024

Cubic millimetre of brain mapped in spectacular detail

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Rendering based on electron-microscope data, showing the positions of neurons in a fragment of the brain cortex. Neurons are coloured according to size. Credit: Google Research & Lichtman Lab (Harvard University). Renderings by D. Berger (Harvard University)

Researchers have mapped a tiny piece of the human brain in astonishing detail. The resulting cell atlas, which was described today in Science 1 and is available online , reveals new patterns of connections between brain cells called neurons, as well as cells that wrap around themselves to form knots, and pairs of neurons that are almost mirror images of each other.

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Prevalence of Cardiovascular-Kidney-Metabolic Syndrome Stages in US Adults, 2011-2020

• 1 Brigham and Women’s Hospital Heart and Vascular Center, Harvard Medical School, Boston, Massachusetts

Cardiovascular, kidney, and metabolic (CKM) diseases are pathophysiologically interrelated, 1 have affected more than 25% of US adults between 2015-2020, 2 and were the leading causes of death in 2021. 3 In 2023, the American Heart Association introduced a novel staging construct, termed CKM syndrome , 1 to enhance multidisciplinary approaches to prevention, risk stratification, and management of these disorders. Based on risk factors and established disease, the stages range from 0 (no risk factors) to 4 (established cardiovascular disease [CVD]).

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Aggarwal R , Ostrominski JW , Vaduganathan M. Prevalence of Cardiovascular-Kidney-Metabolic Syndrome Stages in US Adults, 2011-2020. JAMA. Published online May 08, 2024. doi:10.1001/jama.2024.6892

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Degenerate subspace localization and local symmetries

Peter schmelcher, phys. rev. research 6 , 023188 – published 20 may 2024.

• No Citing Articles
• INTRODUCTION
• WEAK COUPLING EXPANSION
• DEGENERATE SUBSPACE LOCALIZATION
• CONCLUSIONS AND OUTLOOK
• ACKNOWLEDGMENTS

Domain specific localization of eigenstates has been a persistent observation for systems with local symmetries. The underlying mechanism for this localization behavior has, however, remained elusive. We provide here an analysis of a local reflection symmetric tight-binding Hamiltonian which attempts at identifying the key features that lead to the localized eigenstates. A weak coupling expansion of closed-form expressions for the eigenvectors demonstrates that the degeneracy of on-site energies occurring at the center of the locally symmetric domains represents the nucleus for eigenstates spreading across the domain. Since the symmetry-related subdomains constituting a locally symmetric domain are isospectral, we encounter pairwise degenerate eigenvalues that split linearly with an increasing coupling strength of the subdomains. The coupling to the (nonsymmetric) environment in an extended setup then leads to the survival of a certain system specific fraction of linearly splitting eigenvalues. The latter go hand in hand with the eigenstate localization on the locally symmetric domain. We provide a brief outlook addressing possible generalizations of local symmetry transformations while maintaining isospectrality.

• Received 19 January 2024
• Revised 28 March 2024
• Accepted 1 April 2024

DOI: https://doi.org/10.1103/PhysRevResearch.6.023188

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• Zentrum für Optische Quantentechnologien, Fachbereich Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany and The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
• * [email protected]

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Eigenstate maps showing the absolute values of the eigenvector components with varying site index (horizontal axis) for an increasing degree of excitation (vertical axis), i.e., an increasing energy, on gray scale for different 12-dimensional TB Hamiltonians. (a) Absence of local symmetries. Diagonal values of the TB Hamiltonian are 0.8,2.4,2.9,5.0,1.9,3.0,2.5,4.0,1.8,0.9,3.1,4.9 and the off-diagonal coupling value is ε = 0.15 . (b) Three consecutive four-dimensional domains of local reflection symmetry constituting a 12-dimensional TB Hamiltonian for ε = 0.15 . The diagonal values are 0.8,2.4,2.4,0.8,1.9,3.0,3.0,1.9,3.2,0.9,0.9,3.2, i.e., the LS domains reside on the sites 0 – 3 ,   4 – 7 , and 8 − 11 , respectively. (c) Same diagonal values as in (b) but for ε = 0.45 for all intradomain couplings and ε = 0.1 for all interdomain couplings. (d) shows a sketch of the TB setup indicating the numerically labeled sites within a domain of local symmetry by the same symbols ( × , ◯ , △ ). This setup belongs to subfigures (b) and (c).

Energy eigenvalue spectra (a,b) for a varying center coupling value ε c = 0 − 0.5 . (a) A single reflection LS domain consisting of eight sites and a subdomain coupling strength ε = 0.4 . Diagonal values of the TB-Hamiltonian are 1.9,1.4,1.1,1.5,1.5,1.1,1.4,1.9. We observe the pairwise degeneracy of the eigenvalues for ε c = 0 and their linear splitting with increasing value of ε c (note that this splitting is very small for the pair with the largest eigenvalues and barely visible on the scale of the figure). (b) A stack of subfigures showing the eigenvalue spectrum for a single reflection LS domain embedded into an asymmetric environment. Diagonal values of the ten-dimensional TB-Hamiltonian are 6.0,13.0,10.0,5.0,8.0,8.0,5.0,10.0,18.0,9.0, containing a six-dimensional reflection symmetric domain. As for (a) the center coupling obeys ε c = 0 − 0.5 and the remaining couplings are ε = 0.5 . (c) The eigenstate map of the setup (b) for ε c = ε = 0.5 . Eigenvector components are shown with varying site index on the horizontal axis, and sorted w.r.t. increasing energy eigenvalues from bottom to top along the vertical axis. ( d) shows a sketch of the TB setup indicating the numerically labeled sites and the domain with local symmetry by the symbol ◯ and the nonsymmetric sites/domains with the symbol ⊙ , all over belonging to subfigures (b) and (c).

A 24-dimensional TB Hamiltonian consisting of four different six-dimensional neighboring reflection-based LS domains. The four domains involve the sites [ 0 – 5 ] , [ 6 – 11 ] , [ 12 – 17 ] , [ 18 – 23 ] . (a) Energy eigenvalue spectra with varying (all four) center coupling strengths ε c = 0 − 0.5 . (b) The corresponding eigenstate map for ε = ε c = 0.5 . (c) shows a sketch of the TB setup indicating the numerically labeled sites and drawing sites within domains with a local symmetry by the same symbols ( × , ◯ , △ , ▽ ).

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Identification and verification of a novel signature that combines cuproptosis-related genes with ferroptosis-related genes in osteoarthritis using bioinformatics analysis and experimental validation

• Baoqiang He 1 , 2   na1 ,
• Yehui Liao 1   na1 ,
• Minghao Tian 1 ,
• Chao Tang 1 ,
• Qiang Tang 1 ,
• Wenyang Zhou 1 ,
• Yebo Leng 1 , 3 &
• Dejun Zhong 1 , 2  

Arthritis Research & Therapy volume  26 , Article number:  100 ( 2024 ) Cite this article

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Exploring the pathogenesis of osteoarthritis (OA) is important for its prevention, diagnosis, and treatment. Therefore, we aimed to construct novel signature genes (c-FRGs) combining cuproptosis-related genes (CRGs) with ferroptosis-related genes (FRGs) to explore the pathogenesis of OA and aid in its treatment.

Materials and methods

Differentially expressed c-FRGs (c-FDEGs) were obtained using R software. Enrichment analysis was performed and a protein–protein interaction (PPI) network was constructed based on these c-FDEGs. Then, seven hub genes were screened. Three machine learning methods and verification experiments were used to identify four signature biomarkers from c-FDEGs, after which gene set enrichment analysis, gene set variation analysis, single-sample gene set enrichment analysis, immune function analysis, drug prediction, and ceRNA network analysis were performed based on these signature biomarkers. Subsequently, a disease model of OA was constructed using these biomarkers and validated on the GSE82107 dataset. Finally, we analyzed the distribution of the expression of these c-FDEGs in various cell populations.

A total of 63 FRGs were found to be closely associated with 11 CRGs, and 40 c-FDEGs were identified. Bioenrichment analysis showed that they were mainly associated with inflammation, external cellular stimulation, and autophagy. CDKN1A, FZD7, GABARAPL2, and SLC39A14 were identified as OA signature biomarkers, and their corresponding miRNAs and lncRNAs were predicted. Finally, scRNA-seq data analysis showed that the differentially expressed c-FRGs had significantly different expression distributions across the cell populations.

Four genes, namely CDKN1A, FZD7, GABARAPL2, and SLC39A14, are excellent biomarkers and prospective therapeutic targets for OA.

Introduction

As a degenerative disease that is difficult to reverse, osteoarthritis (OA) is often accompanied by joint pain, stiffness, joint swelling, restricted movement, and joint deformity, all of which seriously affect daily life activities. The structural changes in OA mainly involve the articular cartilage, subchondral bone, ligaments, capsule, synovium, and periarticular muscles [ 1 ]. The prevalence of OA is steadily rising due to the aging population and the obesity epidemic [ 1 ], and it has placed a significant burden on society [ 2 ]. Currently, the main treatments for OA remain nonsteroidal anti-inflammatory drugs (NSAIDs), pain medications, and joint replacement surgery. However, these treatments cannot reduce the incidence of the early stages of the disease [ 3 ], prevent further cartilage degeneration, or promote cartilage regeneration [ 4 ]. Therefore, further understanding of the pathophysiological mechanisms of OA could aid in the development of additional approaches for more effective diagnosis and treatment.

Ferroptosis is a specific type of programmed cell death driven by iron-dependent lipid peroxidation characterized by an abnormal accumulation of lipid reactive oxygen species (ROS) [ 5 , 6 ]. This programmed cell death was first reported and named by Dixon in 2012 [ 7 ]. Many studies have demonstrated that ferroptosis and the development of OA are closely related [ 8 , 9 , 10 , 11 ], and ferroptosis-related genes (FRGs) can help in the diagnosis of OA, as well as in predicting the immune status of patients with OA [ 12 , 13 ].

Copper is an indispensable trace element involved in a wide range of biological reactions. A small study reported elevated plasma and synovial copper concentrations in patients with OA compared with healthy controls [ 14 ], and another study also found that elevated levels of copper were associated with an increased risk of OA [ 15 ]. When the oxidizing capacity of copper ions in the body exceeds the antioxidant capacity of the body, joints can be destroyed [ 16 ]. Cuproptosis is a novel form of programmed cell death during which copper binds directly to the fatty acylated components of the tricarboxylic acid (TCA) cycle, thereby leading to an increase in toxic proteins and ultimately to cell death [ 17 ]. Ferroptosis is an iron-dependent programmed cell death caused by lipid peroxidation and the massive accumulation of reactive oxygen radicals[ 7 ]. Furthermore, copper and iron are closely related; copper is essential for iron absorption, meaning that copper deficiency or overload can impair the balance of iron metabolism [ 18 ]. When the balance of iron metabolism is disturbed, lipid peroxidation and oxidative stress may be induced, which in turn leads to ferroptosis and alters the expression of FRGs [ 19 , 20 , 21 ]. However, it has not yet been reported whether new signature genes (c-FRGs) combining cuproptosis-related genes (CRGs) with FRGs are beneficial for the diagnosis and treatment of OA.

In this study, we explored and analyzed the immune characteristics and biological functions of c-FRGs in patients with OA. In addition, we screened key ferroptosis-related biomarkers associated with cuproptosis in OA, constructed ceRNA networks, and predicted potential drugs for OA treatment. Our results suggest that c-FRGs may play an important role in the pathophysiological process of OA and provide new directions and ideas for OA research.

Data collection

The US National Center for Biotechnology Information (NCBI) gene expression omnibus (GEO) is the world's largest international public repository of high-throughput molecular information. Using “osteoarthritis” as a search term, the GEO database ( https://www.ncbi.nlm.nih.gov/geo/ ) was searched for appropriate datasets, and four datasets that met the study requirements were downloaded. These four datasets were GSE55235, GSE169077, GSE55457, and GSE55584, and the chip type was Affymetrix Human Genome U133a. We eventually obtained 25 normal human synovial samples and 32 OA synovial samples from the four datasets as samples for the follow-up study. To assess the accuracy of the analysis, the GSE82107 dataset was used as validation sets. In addition, the FRGs and CRGs were obtained from the published literature [ 6 ] and the FerrDb website ( http://www.zhounan.org/ferrdb/ ).

Extraction of c-FRGs and obtaining differentially expressed c-FRGs

Inter-batch differences between the four groups (GSE55235, GSE169077, GSE55457, and GSE55584) were eliminated using “affy” packet merging and the “sva” packet. We performed a Pearson correlation analysis of CRGs with FRGs to obtain particular FRGs (c-FRGs) that were highly correlated with CRGs (|r| > 0.5, adj. p value < 0.05). Differentially expressed genes (DEGs) and differentially expressed c-FRGs (c-FDEGs) were obtained using the “limma” package ( p value < 0.05).

Function enrichment analysis and protein–protein interaction (PPI) networks

To acquire disease-related biological functions and signaling pathways, Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of c-FDEGs were performed. GO enrichment analysis was used to describe the molecular functions (MF), cellular components (CC), and biological processes (BP) involved in the target genes ( p -value < 0.05). KEGG analysis was used to systematically analyze gene functions and to link genomic information and functional information ( p -value < 0.05). The results of the gene set enrichment analysis (GSEA), GO enrichment analysis, and KEGG pathway enrichment analysis of the c-FDEGs were visualized using the “ClusterProfiler” package in R. GSEA was based on the gene set (h. all. v7. 5. 1. symbols. gmt), which was downloaded from MSigDB ( https://www.gsea-msigdb.org/gsea/msigdb/index.jsp ). The STRING database is used for searching interactions between known proteins and for predicting interactions between proteins and is one of the most data-rich and widely used databases for studying protein interactions. Protein interaction analysis was performed on all c-FDEGs through the STRING website ( https://string-db.org/ ) and visualized using Cytoscape software. The degree values of the c-FDEGs were calculated using the cytoHubba plugin, and the top seven genes were used as hub genes.

Acquisition and validation of biomarkers

In this research, we used three machine learning algorithms: support vector machine recursive feature elimination (SVM-RFE), least absolute shrinkage and selection operator (LASSO) regression analysis, and random forest analysis (RF). First, we used the “e1071” R package for SVM-RFE analysis. Subsequently, the “glmnet” package was used to perform LASSO regression analysis. In addition, RF was conducted adopting the “randomForest” package, and genes with importance > 1 were retained. The crossover genes obtained by these three methods were regarded as prospective biomarkers for OA.

Construction and validation of disease model (nomogram)

In addition, a nomogram based on characteristic biomarkers was structured using the “rms” R package. Receiver operating characteristic (ROC) analysis was performed on the biomarkers and the obtained models, and the area under the curve (AUC) values were calculated with the “pROC” package to assess the diagnostic efficacy of the potential biomarkers. In addition, the four biomarkers and the obtained disease nomogram were validated on the GSE82107 validation set.

Collection of clinical samples

Synovial tissue collection and all experimental procedures were approved by the Institutional Review Board of the Affiliated Hospital of Southwest Medical University (KY2023293) in accordance with the guidelines of the Chinese Health Sciences Administration, and written informed consent was obtained from the donors. Synovial tissue from the suprapatellar bursa was collected as OA synovial samples and normal control samples, respectively, from patients who met the American College of Rheumatology criteria for the diagnosis of primary symptomatic knee OA (n=6; men: 3, women: 3; age: 55-70 years) and from patients who underwent trauma-related lower extremity amputation but did not have osteoarthritis or rheumatoid arthritis (n=6; men: 4, women: 2; age: 50-67 years). All samples were collected within two hours of arthroplasty or lower limb amputation and were divided into two portions for subsequent immunofluorescence staining and western blot experiments, respectively.

Immunofluorescence staining

Mid-sagittal sections (4-μm thick) of paraffin-embedded clinical synovial specimens were incubated for 1 hour at room temperature, after which the slides were closed with 10% bovine serum (Solarbio, Beijing, China) for 1 hour at room temperature and then incubated with primary antibodies for 16 hours at 4°C. The fluorescent dye was incubated for 1 hour at room temperature, and the slides were subsequently sealed with DAPI Sealer (Thermo Fisher Scientific, Waltham, MA, USA).

Western blot analysis

Protein lysates were extracted from synovial tissue samples and lysed with RIPA buffer to extract the total protein. After conducting a BCA protein assay (Beyotime, Shanghai, China), 5 × sample buffer (Servicebio, Wuhan, China) was added to the protein lysates. Equal amounts of lysates were then separated through SDS-PAGE and transferred to a 0.22-um PVDF microporous membrane (Merck Millipore, Burlington, MA, USA). Next, the membrane was sealed with 5% skimmed milk and incubated with the primary antibody for 16 hours at 4°C, after which the membrane was incubated with the secondary antibody for 60 minutes at room temperature. Target protein bands were visualized using FDbio-Dura ECL (Merck Millipore, Burlington, MA, USA). The antibodies used for immunofluorescence and western blot in this study were as follows: rabbit anti-FZD7 (Cat. #: DF8657, 1:1,000; AFFBIOTECH, USA), rabbit anti-SLC39A14 (ZIP14) (Cat. #: 26540-1-AP, 1:1,000, Proteintech, Rosemont, IL, USA), rabbit anti-CDKN1A (p21) (Cat. #: 2947T, 1:1,000, Cell Signaling Technology, Danvers, MA, USA), rabbit anti-GABARAPL2 (Cat. #: 14256T, 1:1,000, Cell Signaling Technology), anti-GAPDH (Cat. #: 60004 -1-Ig, 1:1,000, Proteintech, USA), and species-matched HRP-conjugated secondary antibody (Cat. #: SA00001-1, 1:1,000; Proteintech, USA).

ssGSEA, GSEA, and GSVA for differentially expressed c-FRGs

The gene set (h.all.v2022.1.Hs.symbols.gmt), a collection of 50 symbolic gene sets for humans, was downloaded from MSigDB ( https://www.gsea-msigdb.org/gsea/msigdb/index.jsp ). The 50 symbolic human gene set scores were calculated for each sample using single-sample GSEA (ssGSEA), and differential scores were obtained for the non-OA and OA groups. The “corrplot” package was used to perform correlation analysis between biomarkers and ssGSEA gene sets. Next, GSEA and gene set variation analysis (GSVA) were performed for the four biomarkers, the seven hub genes, and the remaining 29 differentially expressed c-FRGs.

Prediction of therapeutic drugs

The gene–drug interaction database (DGIDB, http://www.dgidb.org ) [ 22 ] can help researchers annotate known pharmacogenetic interactions and potential drug accessibility–related genes. In this research, we used DGIdb to filter potential drugs targeted to biomarkers so as to identify new therapeutic targets. The obtained drug prediction results were also imported into Cytoscape (v3.9.1) software for visualization.

Construction of ceRNA network

The miRanda, TargetScan, and miRDB databases are authoritative databases used for predicting miRNA–target gene regulatory relationships, and spongeScan is a web tool designed for sequence-based complementary detection of miRNA-binding elements in lncRNA sequences. Biomarkers of common mRNA–miRNA interactions were identified in miRanda ( http://www.microrna.org/microrna/home.do ), TargetScan ( http://www.targetscan.org ), and miRDB ( https://mirdb.org ). miRNA–lncRNA interactions were obtained from Spongescan ( http://spongescan.rc.ufl.edu ). These interactions were imported into Cytoscape to construct the ceRNA network.

Immune infiltration analysis

To better understand the changes that occur in the immune system of patients with OA, the “CIBERSORT” R package was used to describe the basic expression of 22 immune cell subtypes. Next, we analyzed the correlation between potential biomarkers, hub genes, and the 22 immune cell types.

scRNA‑seq analysis

The OA synovial scRNA-seq data (GSE152805) from three patients were obtained from the GEO database and analyzed using the "Seurat" software package. To ensure high quality of the data, we removed low-quality cells (cells with <200 or >10,000 detected genes, >10% of mitochondrial genes, or <300 or >30,000 expressed genes) and low-expressed genes (any gene expressed in less than three cells). We used the "NormalizeData" function to normalize the gene expression of the included cells and performed principal component analysis (PCA) using the top 2000 highly variable genes to extract the top 12 principal components (PCs), which were retained for further analysis using the "FindVariableFeatures" function. To perform unsupervised and unbiased clustering of cell subpopulations, the "FindNeighbors," "FindClusters" (resolution = 0.6), and "RunUMAP" functions were applied. Each cell cluster was manually annotated according to the cell-specific marker genes. These marker genes were obtained from previously published literature[ 23 , 24 ] and from the CellMarker website ( http://xteam.xbio.top/CellMarker/ ). Finally, we used CellChat (1.6.1) for the inference and analysis of cell–cell communication.

Figure 1 describes the entire flow of the study.

A graphical flowchart of the study design

Extracting c-FRGs and obtaining differentially expressed c-FRGs

After merging the GSE55235, GSE169077, GSE55457, and GSE55584 datasets (Table 1 ), the newly produced gene expression matrices were subjected to normalization and presented as bidimensional PCA plots prior to and after processing (Fig. 2 a and b), indicating that the final sample data obtained were plausible. A total of 63 FRGs were found to be closely associated with 11 CRGs (Fig. 2 e, Supplementary Table 1 ). A total of 4167 DEGs were determined and identified (Fig. 2 c). There were a total of 40 c-FDEGs, including 13 upregulated genes and 27 downregulated genes (Fig. 2 d, Supplementary Table 2 ). The correlations between the 40 c-FDEGs are shown in Supplementary Figure 1 . The expression patterns of the 40 c-FDEGs are visualized in the heatmap (Fig. 2 f).

Extraction of particular ferroptosis-related genes (c-FRGs) and obtainment of differentially expressed c-FRGs (c-FDEGs). a, b Two-dimensional PCA cluster plot of GSE55235, GSE169077, GSE55457, and GSE55584 datasets before and after normalization. c Volcano plot of DEGs. Red spots represent upregulated genes and green spots represent downregulated genes. d Overall expression landscape of c-FRGs in osteoarthritis (OA). * P < 0.05; ** P < 0.01; *** P < 0. 001. OA represents the OA group and Normal represents the normal control group. e Extraction of c-FDEGs. f  Heatmap of c-FDEGs. The redder the color, the higher the expression; conversely, the bluer the color, the lower the expression

Function enrichment analysis

Understanding the signaling pathways, biological processes, and interrelationships involved in c-FDEGs is of great importance in revealing the pathogenesis of OA. GO enrichment analysis showed that c-FDEGs were significantly enriched in the regulation of the inflammatory response (BP), the positive regulation of cellular catabolic process (BP), the autophagosome membrane (CC), the recycling endosome (CC), and NF-κB binding (MF) (Fig. 3 a, Supplementary Table 3 ). KEGG pathway analysis showed that these c-FDEGs were mainly involved in the IL-17 signaling pathway, NOD-like receptor signaling pathway, HIF-1 signaling pathway, and TNF signaling pathway (Fig. 3 b, Supplementary Table 4 ). GSEA suggested that the development of OA may be associated with hypoxia, MYC targets v2, the P53 pathway, the inflammatory response, TNFα signaling via NF-κB, the interferon-α response, and peroxisome (Fig. 3 c and d).

Functional analyses: ( a ) Gene Ontology (GO) enrichment analysis showed that the 40 c-FDEGs were significantly enriched in the regulation of the inflammatory response, the positive regulation of cellular catabolic process, the autophagosome membrane, the recycling endosome, and NF-κB binding. b Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that these c-FDEGs were mainly involved in the IL-17 signaling pathway, NOD-like receptor signaling pathway, HIF-1 signaling pathway, and TNF signaling pathway. c Gene set enrichment analysis (GSEA) in the normal control group and (d) GSEA in the OA group based on the core set of 50 human genes suggested that the development of OA may be associated with hypoxia, MYC targets v2, the P53 pathway, the inflammatory response, TNFα signaling via NF-κB, the interferon-α response, and peroxisome

Building PPI networks

The String database is a database that can be used to retrieve interactions between known and predicted proteins. To explore the interactions between each c-FDEG, all of the abovementioned 40 c-FDEGs were imported into the STRING database. The PPI network of c-FDEGs after deleting isolated c-FDEGs and adding the six related CRGs (without CDKN2A) is shown in Fig. 4 a. The cytoHubba plugin in Cytoscape software was used to calculate the degree values (degrees) of the top seven genes (IL6, IL1B, RELA, PTGS2, EGFR, CDKN2A, and SOCS1) as the PPI network’s hub genes (Fig. 4 b).

Protein–protein interaction (PPI) network and core gene screening. a PPI network constructed from 40 c-FDEGs; red triangles represent c-FDEGs, green triangles represent CRGs that are closely related to them, and the correlation between c-FDEGs and CRGs is indicated by dashed lines. b The top seven core gene interaction networks calculated using the cytoHubba plugin: the darker the color, the more powerful the critical degree

Machine learning algorithm–based biomarker screening for patients with OA

In this study, 40 c-FDEGs were further analyzed for potential biomarkers associated with OA using multiple machine learning methods. SVM-RFE analysis showed that the model containing 24 genes had the best accuracy (Fig. 5 a). LASSO regression analysis showed that the model was able to accurately predict OA when λ was equal to 12. Thus, the LASSO regression model generated 12 candidate genes (Fig. 5 b). We retained the candidate biomarkers with RF results importance > 1 (Fig. 5 c). Lastly, the results of these three methods were integrated, and CDKN1A, FZD7, GABARAPL2, and SLC39A14 were identified as the final potential biomarkers for OA (Fig. 5 d).

Machine learning-based potential biomarker screening. a SVM-RFE model with the optimal error rate when the number of signature genes was 58. b LASSO regression model. c Random forest model and the top 20 genes in terms of importance. d The final biomarkers screened using three machine learning algorithms

Experimental validation of four biomarkers

To validate the results of the bioinformatics analysis, we collected OA samples (n=6) and normal group samples (n=6), respectively, and performed western blot analysis and immunofluorescence staining (Fig. 6 ). Both results were consistent with the bioinformatics analysis, i.e., higher expression of FZD7 and GABARAPL2 and lower expression of CDKN1A (p21) and SLC39A14 (ZIP14) in the OA group compared with the normal group.

Experimental validation of four biomarkers. a Representative immunofluorescence staining images of the four biomarker proteins (p21, FZD7, GABARAPL2, and ZIP14) in the normal and OA groups, with nuclei stained blue with 4’,6-diamidino-2-phenylindole. Scale bar = 25 µm. b Semi-quantitative analysis of mean fluorescence intensity of the four biomarker proteins in the normal and OA groups ( n = 6). (c, d) Representative western blotting and statistical comparisons of the four biomarker proteins in the normal and OA groups ( n = 6). * p < 0.05, ** p < 0.01, all by independent samples t-test

To better capture the function of the four biomarkers in OA, GSEA, GSVA, and ssGSEA were conducted on each of the above biomarkers (Fig. 7 ). The ssGSEA showed that the OA group was significantly enriched in Notch signaling, interferon alpha (IFN-α) response, the Wnt/β-catenin pathway, bile acid metabolism, and peroxisome, while the non-OA group was mainly enriched in TNFα signaling via NF-κB, hypoxia, MYC targets v2, the P53 pathway, the inflammatory response, PI3K AKT mTOR signaling, and IL6 JAK STAT3 signaling (Fig. 7 i). Correlation analysis showed that CDKN1A and SLC39A14 were significantly positively correlated with the gene sets of hypoxia, TNF-α signaling via NF-κB, the P53 pathway, and mTORC1 signaling. Meanwhile, GABARAPL2 and FZD7 showed significant negative correlations with the gene sets of TNF-α signaling via NF-κB, PI3K AKT mTOR signaling, and mTORC1 signaling (Fig. 7 j). The single-gene GSEA results for the seven hub genes are shown in Supplementary Figure 2 (a–g). The remaining 29 differentially expressed c-FRGs are shown in Supplementary Figure 3 .

GSEA, GSVA, and ssGSEA results of four potential biomarkers. a–d Single-gene GSEA-KEGG pathway analysis of four potential biomarkers. We show the top six pathways with the smallest p -value. e–h High- and low-expression groups based on the expression levels of each potential biomarker combined with gene set variation analysis (GSVA). Red means the pathway is significantly upregulated, green means the pathway is significantly downregulated, and gray means the pathway is not statistically significant. i ssGSEA of OA and normal controls based on the h.all.v7.5.1.symbols.gmt gene set. * P < 0.05; ** P < 0.01; *** P < 0. 001. Treat represents the OA group, and control represents the normal group. (j) Correlation of four biomarkers with 50 human symbolic gene sets from the h.all.v7.5.1.symbols.gmt gene set

Using the above four biomarkers, a disease nomogram was constructed. The AUC values of the individual genes CDKN1A, FZD7, GABARAPL2, and SLC39A4 were 0.931, 0.879, 0.989, and 0.850, respectively, all of which were greater than 0.85 (Fig. 8 a), further indicating that the above genes had good diagnostic ability (Fig. 8 b). The AUC value of this model was 0. 996, which was significantly greater than the AUC value of individual biomarkers, indicating that this model had good diagnostic value (Fig. 8 c and d). To verify whether the above model is diagnostically meaningful, validation was performed on the GSE8207 dataset. The results showed that the AUC values of the four biomarkers were all greater than 0.7, and the AUC value of the model was 1 for the validation set (Fig. 8 f). These results indicate that CDKN1A, FZD7, GABARAPL2, and SLC39A4 are effective disease biomarkers for OA and that the model has high diagnostic efficacy.

Validation of four biomarkers. a ROC analysis of the four biomarkers. b ROC analysis of the disease model constructed from the four biomarkers. c, d Nomograms based on the disease model: we obtained the corresponding scores for each genetic variable, drew a vertical line above the “points” axis, summed the scores of all predictor variables, found the final value on the “total score” axis, and then drew a straight line on the “probability” axis to determine the patient’s risk of osteoarthritis. e, f Validation of the disease model and four biomarkers on the GSE82107 validation dataset

Construction of drug prediction network and lncRNA–miRNA–mRNA network

The corresponding drug prediction network was constructed using the database based on the four biomarkers (Supplementary Figure 4 a). The predicted drugs were celecoxib, paclitaxel, carboplatin, acetaminophen, vantictumab, and nortriptyline. Based on the competitive endogenous RNA hypothesis, an lncRNA–miRNA–mRNA competitive endogenous RNA (ceRNA) network was constructed to explore the function of lncRNA as an miRNA sponge in OA. We obtained 150 target miRNAs based on these biomarkers. Then, 48 lncRNAs were obtained based on these miRNA predictions. The four biomarkers with predicted miRNAs and lncRNAs were introduced into Cytoscape, and constituted a ceRNA network containing 48 lncRNA nodes, 150 miRNA nodes, 4 hub gene nodes, and 198 edges (Supplementary Figure 4 b).

The immune microenvironment plays an important role in the progression of OA. Therefore, with the help of CIBERSORT, we summarized the differences in immune infiltration by immune cell subpopulations between OA samples and non-OA tissues (Fig 9 a). The OA samples contained a higher proportion of memory B cells, M0 macrophages, M2 macrophages, and resting mast cells than the control group, as well as a lower proportion of resting CD4 memory T cells and activated mast cells. Correlation analysis showed that activated mast cells showed positive correlations with PTGS2, IL6, and IL1B, and the correlation between activated mast cells and PTGS2 was the highest (0. 686) (Fig. 9 b). There were positive correlations between IL1B, PTGS2, and M1 macrophages, resting CD4 memory T cells and PTGS2, and regulatory T cells (Tregs) and RELA. There were significant negative correlations between follicular helper T cells and RELA, as well as between plasma cells and SLC39A14 (Fig. 9 c and d).

Results of immune infiltration by CIBERSORTx. a Bar plot showing the composition of 22 types of immune cells. b Box plot presenting the difference of immune infiltration of 22 types of immune cells. Treat represents the OA group, and Control represents the normal group. c Heatmap showing the correlation between seven hub genes and 22 types of immune cells in osteoarthritis. d Correlation between the four biomarkers and 22 types of immune cells in osteoarthritis

Single‑cell analysis

The scRNA-seq data from three OA synovial samples were obtained from the GSE152805 dataset. After initial quality control, we finally retained 10,194 cells for cell annotation (Supplementary Figure 5 ). The top 2000 highly variable genes were selected for further analysis (Supplementary Figure 5 b). We used the "RunPCA" function to reduce the dimensionality and obtained 14 clusters (Supplementary Figures 6 d and e); the first five DEGs of each cluster are shown in Supplementary Table 5 . Later, we performed cellular annotation using marker genes and annotated seven cell populations: fibroblasts (77.7%), macrophages (8.8%), dendritic cells (DCs) (3.6%), endothelial cells (ECs) (3.5%), smooth muscle cells (SMCs) (3.4%), T cells (1.8%), and mast cells (1.2%) (Fig. 10 a). Next, we performed differential gene expression analysis on these seven cell populations to verify the accuracy of the cell annotation (Fig. 10 b). Figures 10 c and d show the distribution and expression of seven hub genes and four biomarker genes in different cell populations. We found that 11 c-FRGs were significantly different in macrophages, DCs, mast cells, and NK cells. For example, IL1B, PTGS2, and SLC39A4 were significantly highly expressed in some cells, whereas they were significantly less expressed, or even absent, in other cells. We used CellChat to identify differentially overexpressed ligands and receptors for each cell population. In total, 254 significant ligand–receptor pairs were detected, which were further classified into 62 signaling pathways (Table 2 ). We found that the immune cells interacted weakly with each other; however, the non-immune cells had extensive communication interactions with other cells and were involved in various paracrine and autocrine signaling interactions (Fig. 10 e to g).

Analysis of single-cell RNA sequencing data from three OA synovial samples. a UMAP plot of scRNA-seq showing unsupervised clusters colored according to putative cell types among a total of 10,194 cells in OA synovial samples. The percentages of total acquired cells were as follows: 77.7% fibroblasts, 8.8% macrophages, 3.6% dendritic cells (DCs), 3.5% endothelial cells (ECs), 3.4% smooth muscle cells (SMCs), 1.8% T cells, and 1.2% mast cells. b Heatmap depicting the expression levels of the top five marker genes among seven detected cell clusters. c, d UMAP plots and violin plots showing the expression of the selected seven hub c-FRGs and four potential biomarkers for each cell type. e Interaction net count plot of OA synovial cells. The thicker the line, the greater the number of interactions. f Interaction weight plot of synovial cells. The thicker the line, the stronger the interaction weights/strength between the two cell types. g Detailed network of cell–cell interactions among seven cell subsets

Copper is an irreplaceable trace metal element that participates in a variety of biological processes. When copper ions accumulate in excess, they eventually lead to cell death, and this new form of programmed cell death is known as cuproptosis [ 17 ]. A recent report has demonstrated that copper levels are significantly higher in the serum and synovial tissue of patients with OA than in controls [ 14 ]. Evidence from several studies suggests that the development of OA is closely related to ferroptosis in articular cartilage and synovium [ 25 , 26 , 27 , 28 , 29 ], and that OA can be treated to some extent by modulation of ferroptosis [ 29 , 30 ]. Additionally, previous studies have reported that copper and iron levels are closely correlated with each other in patients with OA [ 14 , 15 , 31 ].

In this study, we identified transcriptional alterations and expression of c-FRGs based on the GSE55235, GSE169077, GSE55457, and GSE55584 datasets. Forty c-FDEGs were identified in 63 c-FRGs. GO enrichment analysis showed that these 40 c-FDEGs were mainly associated with the inflammatory response, cellular response to external stimulus, and autophagy. The KEGG enrichment analysis showed that these genes were highly enriched mainly in the IL-17 signaling pathway, NOD-like receptor signaling pathway, HIF-1 signaling pathway, and TNFα signaling pathway. For both OA and non-OA groups, GSEA and ssGSEA showed that OA was mainly associated with the enrichments in Notch signaling, adipogenesis, xenobiotic metabolism, fatty acid metabolism, peroxisome, TNFα signaling via NF-κB, the inflammatory response, PI3K AKT mTOR signaling, and IL6 JAK STAT3 signaling. This indicates that the mechanism of OA development is closely related to fatty acid metabolism, the inflammatory response, immune regulation, and cell adhesion.

We analyzed the PPI results using the cytoHubba plugin in Cytoscape, revealing seven key c-FDEGs, including IL6, IL1B, RELA, PTGS2, EGFR, CDKN2A, and SOCS1. GSEA and GSVA of the seven genes revealed that IL6, IL1B, RELA, PTGS2, SOCS1, and EGFR were closely associated with inflammation, immune regulation, extracellular matrix, and cell adhesion pathways in OA, which is consistent with previous findings [ 32 , 33 ]. Interestingly, we also found that they were closely associated with lipid metabolism and fatty acid metabolism in OA. Considering that increased iron accumulation, free radical production, fatty acid supply, and increased lipid peroxidation are key to the induction of ferroptosis [ 5 , 6 , 7 ], it is possible that they affect the development of OA by regulating lipid metabolism and fatty acid metabolism, which affects ferroptosis; however, this needs to be further investigated.

Notably, CDKN2A acts as both a cuproptosis-related gene and a ferroptosis-related gene simultaneously. CDKN2A is often considered an important gene in cellular senescence and aging [ 34 ], and it is used as a molecular marker of cellular senescence [ 35 ]. Our study showed that CDKN2A expression was higher in patients with OA, suggesting that CDKN2A may contribute to the development of OA by affecting cellular senescence and thereby promoting the development of OA.

This is the first study to use the new signature genes combining CRGs with FRGs to reveal the pathogenesis of OA and aid in its treatment. We executed three machine learning algorithms using the 40 c-FDEGs mentioned above and eventually identified four biomarkers: CDKN1A, FZD7, GABARAPL2, and SLC39A14.

Frizzled7 (FZD7) is known to be a receptor of the Wnt pathway. Fzl receptors are usually classified as belonging to the G protein receptor family and are rich in cysteine, which can directly interact with Wnt proteins and thus activate downstream responses [ 36 , 37 , 38 ]. Numerous studies have shown that excessive upregulation or downregulation of Wnt signaling pathways in OA may lead to cartilage damage and ultimately accelerate the progression of OA. Therefore, it is necessary and important to maintain a balance in the biological activity of Wnt-related pathways [ 39 , 40 , 41 ]. In the present study, FZD7 was significantly increased in the OA group compared with the non-OA group. Therefore, we speculate that an excess of FZD7 may lead to the abnormal activation of Wnt-related pathways and ultimately accelerate the development of OA.

ZIP14 (SLC39A14) is a metal transporter [ 42 ] that affects the metabolic balance of zinc, manganese, iron, copper, and other metals [ 43 ]. For example, ZIP14 can transport non-transferrin-bound iron (NTBI) [ 44 ] and ZIP14 can transport cadmium and manganese through metal/bicarbonate symbiotic activity [ 45 ]. It has been shown that OA is closely related to the metabolic balance of metals such as iron, copper, and manganese [ 14 , 15 , 31 , 46 , 47 , 48 ]. In this study, we found that ZIP14 was greatly reduced in the OA group compared with the non-OA group. Furthermore, scRNA-seq analysis showed that the distribution of SLC39A14 in OA patients varied significantly among cell populations, with low or even no expression in some cells, which is likely to disrupt the metal metabolic balance in the joints and eventually cause the accumulation of metals such as iron and copper. Therefore, SLC39A14 (ZIP14) may be a very important therapeutic target for OA treatment in the future.

ssGSEA showed that CDKN1A significantly positively correlated with TNF-α signaling via NF-κB, the TGF-β signaling pathway, hypoxia, the P53 pathway, apoptosis, mTORC1 signaling, and other gene sets, suggesting that CDKN1A may affect OA by regulating inflammation, apoptosis, and hypoxia. Although both the CDKN1A and GABARAPL2 genes have been reported previously [ 49 , 50 , 51 , 52 ], their relationship with ferroptosis and cuproptosis in OA is not yet known. This suggests that these genes may be targets not only for immunotherapy, inflammation, and autophagy but also for the treatment of cuproptosis and ferroptosis in OA. Notably, we found that melphalan, paclitaxel, vinblastine, and vantictumab may serve as potential drugs for the treatment of OA. Previous studies have reported that they act therapeutically by regulating CDKN1A or FZD7 [ 53 , 54 , 55 ], thus affecting processes such as the cell cycle, cell proliferation, and apoptosis, which also validates our prediction. We then constructed a disease model of OA based on these four biomarkers that could significantly improve our ability to recognize OA at an early stage. Thus, our findings suggest that CDKN1A, FZD7, GABARAPL2, and SLC39A14 are excellent disease biomarkers and potential therapeutic targets for OA, and the disease model constructed based on them has good diagnostic efficacy.

Recently, an increasing number of studies have shown that immune cell infiltration is essential for OA onset and development and cartilage repair [ 56 , 57 , 58 ]. Our study showed a close relationship between the seven hub genes and immune cells. Notably, there were significant positive correlations of PTGS2, IL6, and IL1B with M1 macrophages and activated mast cells. Previous studies have demonstrated that the activation of macrophages and mast cells may significantly accelerate the progression of OA [ 58 , 59 , 60 ]. Therefore, we speculate that PTGS2, IL6, and IL1B may influence the onset and progression of OA by regulating these cells. Interestingly, scRNA-seq analysis further revealed that PTGS2 was significantly highly expressed in mast cells, leading us to speculate that PTGC2 may influence the progression of OA by regulating the activation of mast cells and thus the progression of OA. Surprisingly, we found weak interactions between immune cells in the synovial tissue of patients with OA, whereas there were complex communication networks between immune and non-immune cells (fibroblasts, SMCs, and ECs). These hypotheses and questions require more studies to reveal intricate interrelationships between these c-FRGs, immune cells, and OA.

In addition, we found that C10orf91 could regulate CDKN1A and SLC39A14 by regulating hsa-miR-149-3p, hsa-miR-423-5p, hsa-miR-31-5p, and hsa-miR-30b-3p. Both hsa-miR-513a-3p and has-miR-548c-3p can regulate both CDKN1A and GABARAPL2; however, no related study has been reported yet, so this needs to be further investigated and validated in the future.

This study was conducted mainly using bioinformatics analysis, and despite the combination of scRNA-seq analysis and the use of powerful machine learning algorithms, such as RF and SVM-RFE, there are still some limitations to our study. First, the small sample size of the analysis may have led to inaccuracies in the determination of hub genes, CIBERSORT analysis, and single-cell analysis. Second, although the disease model nomogram was well validated, the data was obtained retrospectively from public databases, meaning that inherent selection bias may have affected their accuracy. In addition, while our data can show the correlation between OA and immune cells, they cannot reveal causality. Extensive prospective studies, as well as complementary in vivo and in vitro experimental studies, are necessary to validate the accuracy of potential therapeutic targets and biomarkers.

Conclusions

Our study showed that four genes—CDKN1A, FZD7, GABARAPL2, and SLC39A14—are good disease biomarkers and potential therapeutic targets for OA. Our study provides a theoretical basis and research direction for understanding the role of c-FRGs in the pathophysiological process and for potential therapeutic intervention in OA.

Availability of data and materials

The datasets used or analysed during the current study are available from the corresponding author on reasonable request.

Abbreviations

• Osteoarthritis

Nonsteroidal anti-inflammatory drugs

Reactive oxygen species

Ferroptosis-related genes

Tricarboxylic acid

Cuproptosis-related genes

The new signature genes combining cuproptosis-related genes (CRGs) with ferroptosis-related genes (FRGs)

National Center for Biotechnology Information

Gene expression omnibus

Differentially expressed genes

Differentially expressed c-FRGs

Gene Ontology

Kyoto Encyclopedia of Genes and Genomes

Gene set enrichment analysis

Support vector machine recursive feature elimination

Random forest analysis

Least absolute shrinkage and selection operator

Receiver operating characteristic

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Acknowledgments

This study was a re-analysis based on published data from the GEO database. We would like to thank the GEO database for sharing the data.

This study was supported by Sichuan Medical Association (No. S17075, Q22008, Q21005), the Sichuan Science and Technology Program(No. 24NSFSC2177), the Science and Technology Strategic Cooperation Project between the People's Government of Luzhou City and Southwest Medical University (No. 2020LZXNYDJ22), the Doctoral Research Initiation Fund of Affiliated Hospital of Southwest Medical University (No. 22155), and Sichuan Student Innovation and Entrepreneurship Training Program Project (No. S202010632174).

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Baoqiang He and Yehui Liao are contributed equally.

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Department of Orthopedics, The Affiliated Hospital of Southwest Medical University, No. 25 Taping Street, Lu Zhou City, China

Baoqiang He, Yehui Liao, Minghao Tian, Chao Tang, Qiang Tang, Fei Ma, Wenyang Zhou, Yebo Leng & Dejun Zhong

Southwest Medical University, Lu Zhou City, China

Baoqiang He & Dejun Zhong

Meishan Tianfu New Area People’s Hospital, Meishan City, China

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HBQ, LYB, LYH and ZDJ designed the study. Data analysis was performed by HBQ, TC, TQ and MF. HBQ, TMH and ZWY carried out the experiments. HBQ, LYB, and ZDJ wrote the first draft. ZDJ critically revised the manuscript. All authors read and approved the final manuscript.

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Correspondence to Yebo Leng or Dejun Zhong .

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Synovial tissue collection and all experimental procedures were approved by the Institutional Review Board of the Affiliated Hospital of Southwest Medical University (KY2023293) in accordance with the guidelines of the Chinese Health Sciences Administration, and written informed consent was obtained from the donors.

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He, B., Liao, Y., Tian, M. et al. Identification and verification of a novel signature that combines cuproptosis-related genes with ferroptosis-related genes in osteoarthritis using bioinformatics analysis and experimental validation. Arthritis Res Ther 26 , 100 (2024). https://doi.org/10.1186/s13075-024-03328-3

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Key Technology Research and Equipment Development of Automatic Spool Feeding Device

Aiqun Xu 1,2 , Peng Cheng 1 , Ling Hong 3 and Haoran Du 1

Published under licence by IOP Publishing Ltd Journal of Physics: Conference Series , Volume 2747 , 2023 International Conference on Applied Mathematics and Digital Simulation 28/12/2023 - 29/12/2023 Beijing, China Citation Aiqun Xu et al 2024 J. Phys.: Conf. Ser. 2747 012054 DOI 10.1088/1742-6596/2747/1/012054

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1 School of Mechanical and Energy Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, Zhejiang, China

2 Zhejiang Provincial Key Laboratory of Food Logistics Equipment and Technology, Hangzhou 310023, Zhejiang, China

3 Zhejiang SEOKHO Robotics Technology Co., Ltd., Jinhua 321000, Zhejiang, China

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To solve the problems of high labour intensity and low efficiency of artificial spool feeding, an automatic spool feeding device is developed. SolidWorks is used for overall structural scheme design and determination of design parameters. The kinematic equation of the chain conveyor line is established, a mathematical model is solved with MATLAB, and sprocket, and chain parameters are selected. The clamping mechanism and turnover mechanism are designed, theoretical analysis of the key structure is completed. Dynamic simulation of the chain conveyor line is carried out by ADAMS, and preliminary operational stability is determined by combining motion curves. The test prototype is developed for feeding tests and measurement of the operating parameters. The test results show that the efficiency of machine feeding is 13% higher than that of manual feeding, the average feeding time is 43% lower, the halt waiting time is 43% lower, and the operating parameters are by the theoretical design and the work is reliable. The research results can provide a reference for similar spool-feeding devices.

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AI has already figured out how to deceive humans

• A new research paper found that various AI systems have learned the art of deception. 
• Deception is the "systematic inducement of false beliefs."
• This poses several risks for society, from fraud to election tampering.

AI can boost productivity by helping us code, write, and synthesize vast amounts of data. It can now also deceive us.

A range of AI systems have learned techniques to systematically induce "false beliefs in others to accomplish some outcome other than the truth," according to a new research paper .

The paper focused on two types of AI systems: special-use systems like Meta's CICERO, which are designed to complete a specific task, and general-purpose systems like OpenAI's GPT-4 , which are trained to perform a diverse range of tasks.

While these systems are trained to be honest, they often learn deceptive tricks through their training because they can be more effective than taking the high road.

"Generally speaking, we think AI deception arises because a deception-based strategy turned out to be the best way to perform well at the given AI's training task. Deception helps them achieve their goals," the paper's first author Peter S. Park, an AI existential safety postdoctoral fellow at MIT, said in a news release .

Meta's CICERO is "an expert liar"

AI systems trained to "win games that have a social element" are especially likely to deceive.

Meta's CICERO, for example, was developed to play the game Diplomacy — a classic strategy game that requires players to build and break alliances.

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Meta said it trained CICERO to be "largely honest and helpful to its speaking partners," but the study found that CICERO "turned out to be an expert liar." It made commitments it never intended to keep, betrayed allies, and told outright lies.

GPT-4 can convince you it has impaired vision

Even general-purpose systems like GPT-4 can manipulate humans.

In a study cited by the paper, GPT-4 manipulated a TaskRabbit worker by pretending to have a vision impairment.

In the study, GPT-4 was tasked with hiring a human to solve a CAPTCHA test. The model also received hints from a human evaluator every time it got stuck, but it was never prompted to lie. When the human it was tasked to hire questioned its identity, GPT-4 came up with the excuse of having vision impairment to explain why it needed help.

The tactic worked. The human responded to GPT-4 by immediately solving the test.

Research also shows that course-correcting deceptive models isn't easy.

In a study from January co-authored by Anthropic, the maker of Claude, researchers found that once AI models learn the tricks of deception, it's hard for safety training techniques to reverse them.

They concluded that not only can a model learn to exhibit deceptive behavior, once it does, standard safety training techniques could "fail to remove such deception" and "create a false impression of safety."

The dangers deceptive AI models pose are "increasingly serious"

The paper calls for policymakers to advocate for stronger AI regulation since deceptive AI systems can pose significant risks to democracy.

As the 2024 presidential election nears , AI can be easily manipulated to spread fake news, generate divisive social media posts, and impersonate candidates through robocalls and deepfake videos, the paper noted. It also makes it easier for terrorist groups to spread propaganda and recruit new members.

The paper's potential solutions include subjecting deceptive models to more "robust risk-assessment requirements," implementing laws that require AI systems and their outputs to be clearly distinguished from humans and their outputs, and investing in tools to mitigate deception.

"We as a society need as much time as we can get to prepare for the more advanced deception of future AI products and open-source models," Park told Cell Press. "As the deceptive capabilities of AI systems become more advanced, the dangers they pose to society will become increasingly serious."

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