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How to cite a research paper in APA, MLA, Chicago, IEEE and Vancouver

Updated 12 min read

Short answer:

To cite a research paper, collect the authors, year, article title, journal, volume, issue, pages and DOI, then arrange them in the order your style requires. APA 7 puts the year after the authors, MLA 9 near the end, Chicago depends on its system, and IEEE and Vancouver number sources. Add a short in-text citation every time you use the paper.

This guide is for students and researchers who need correct academic citations. Every example uses a real paper with a DOI checked on Crossref. It is part of our series on citing real sources with AI.

What do you need to cite a research paper?

A citation is a short, standard description of a source that lets a reader find exactly the work you used. Every style uses the same core facts; only the order, punctuation and capitalization change. Collect them once, from the publisher's article page, and you can produce any style.

ElementWhere to find itExample (LeCun, Bengio and Hinton, 2015)
AuthorsByline on the article pageYann LeCun, Yoshua Bengio, Geoffrey Hinton
YearIssue date or "Published" date2015
Article titleTop of the articleDeep learning
JournalHeader or article pageNature
Volume and issue"Vol." and "No." on the page or PDF header521, 7553
Pages or article numberFirst and last page, or "Article 14045"436–444
DOIArticle page, PDF first page10.1038/nature14539

A DOI (digital object identifier) is a permanent ID for a published work that always resolves to its current page. Crossref, the main DOI agency for journals, recommends displaying it as a full link: https://doi.org/10.1038/nature14539, not "doi:" and not "dx.doi.org" [11]. APA 7, MLA 9 and Chicago follow that form; IEEE and Vancouver still write "doi:".

Cite research paper sources: one paper in five styles

Before you cite research paper sources in your own work, compare one journal article, LeCun, Bengio and Hinton's "Deep learning" in Nature [12], in each style. Note how capitalization, the date position and the page range change.

StyleReference list entryIn-text
APA 7LeCun, Y., Bengio, Y., & Hinton, G. (2015). Deep learning. Nature, 521(7553), 436–444. https://doi.org/10.1038/nature14539(LeCun et al., 2015)
MLA 9LeCun, Yann, et al. "Deep Learning." Nature, vol. 521, no. 7553, 2015, pp. 436–44, https://doi.org/10.1038/nature14539.(LeCun et al. 437)
Chicago 18, author-dateLeCun, Yann, Yoshua Bengio, and Geoffrey Hinton. 2015. "Deep Learning." Nature 521 (7553): 436–44. https://doi.org/10.1038/nature14539.(LeCun et al. 2015, 437)
IEEE[1] Y. LeCun, Y. Bengio, and G. Hinton, "Deep learning," Nature, vol. 521, no. 7553, pp. 436–444, May 2015, doi: 10.1038/nature14539.[1]
Vancouver1. LeCun Y, Bengio Y, Hinton G. Deep learning. Nature. 2015 May 28;521(7553):436-44. doi: 10.1038/nature14539(1) or superscript ¹

How do you cite a research paper in APA 7?

APA 7 uses author, date, title, source: surnames with initials, the year in parentheses, the title in sentence case, the journal and volume in italics, and the DOI as a link [1][5].

Journal article

The journal-article form is in the table above. Sentence case: capitalize only the first word, the first word after a colon, and proper nouns.

Article number instead of pages

Many online journals give each paper an article number. APA writes "Article" and the number where the page range would go [1]:

Walters, W. H., & Wilder, E. I. (2023). Fabrication and errors in the bibliographic citations generated by ChatGPT. Scientific Reports, 13(1), Article 14045. https://doi.org/10.1038/s41598-023-41032-5

The article number never appears in the in-text citation [1].

21 or more authors

APA lists up to 20 authors. With 21 or more, list the first 19, an ellipsis, then the last author [1]. The PRISMA 2020 statement has 26 authors [15]:

Page, M. J., McKenzie, J. E., Bossuyt, P. M., Boutron, I., Hoffmann, T. C., Mulrow, C. D., Shamseer, L., Tetzlaff, J. M., Akl, E. A., Brennan, S. E., Chou, R., Glanville, J., Grimshaw, J. M., Hróbjartsson, A., Lalu, M. M., Li, T., Loder, E. W., Mayo-Wilson, E., McDonald, S., . . . Moher, D. (2021). The PRISMA 2020 statement: An updated guideline for reporting systematic reviews. BMJ, 372, Article n71. https://doi.org/10.1136/bmj.n71

In the text it is simply (Page et al., 2021).

Preprint

For a preprint, italicize the title and give the repository in place of a journal [2]:

Vaswani, A., Shazeer, N., Parmar, N., Uszkoreit, J., Jones, L., Gomez, A. N., Kaiser, L., & Polosukhin, I. (2017). Attention is all you need. arXiv. https://doi.org/10.48550/arXiv.1706.03762

This paper was later published in conference proceedings. If you read that version, cite it instead.

Conference paper

APA treats a paper in published proceedings like a chapter in an edited book [3]:

He, K., Zhang, X., Ren, S., & Sun, J. (2016). Deep residual learning for image recognition. In 2016 IEEE Conference on Computer Vision and Pattern Recognition (CVPR) (pp. 770–778). IEEE. https://doi.org/10.1109/CVPR.2016.90

If the proceedings appear as a journal issue, cite the paper as a journal article.

How do you cite a research paper in MLA 9?

MLA 9 puts the author's full name first, the title in title case inside quotation marks, then the container (the journal) with volume, issue, year and pages [6]:

LeCun, Yann, et al. "Deep Learning." Nature, vol. 521, no. 7553, 2015, pp. 436–44, https://doi.org/10.1038/nature14539.

Four rules:

  1. Three or more authors: first author, then "et al." in both the works-cited entry and the text [6].
  2. Page ranges: "pp." before the range, and the second number shortened where the hundreds repeat: 436–44.
  3. DOI: give it as a link at the end, followed by a period.
  4. In-text: surname and page with no comma, (LeCun et al. 437), or name the authors in the sentence and put only the page in parentheses [6].

How do you cite a research paper in Chicago style?

Chicago has two systems. Notes and bibliography uses footnotes and is common in history and the humanities. Author-date uses (Author Year, page) and is common in the sciences and social sciences [7][8]. Ask which one your department or publisher wants.

Notes and bibliography (Chicago 18)

  1. Yann LeCun et al., "Deep Learning," Nature 521, no. 7553 (2015): 437, https://doi.org/10.1038/nature14539.

  2. LeCun et al., "Deep Learning," 438.

Bibliography: LeCun, Yann, Yoshua Bengio, and Geoffrey Hinton. "Deep Learning." Nature 521, no. 7553 (2015): 436–44. https://doi.org/10.1038/nature14539.

Author-date (Chicago 18)

The reference list entry is in the five-style table above: the year moves up after the authors, and the issue goes in parentheses, 521 (7553). In the text: (LeCun et al. 2015, 437).

What changed between Chicago 17 and 18?

The 18th edition (2024) changed the author rules; check which edition your course uses.

RuleChicago 17Chicago 18
Notes and in-text, "et al." from4 or more authors3 or more authors
Bibliography and reference listList up to 10; with 11 or more, first 7 then et al.List up to 6; with 7 or more, first 3 then et al.
Example note for LeCun (3 authors)Yann LeCun, Yoshua Bengio, and Geoffrey Hinton, ...Yann LeCun et al., ...

Sources: library guides for the 18th edition [7][8].

How do you cite a research paper in IEEE style?

IEEE numbers sources in the order you first cite them and puts the number in square brackets in the text, inside the punctuation [9]. The format is: initials and surname, "Title in sentence case," Abbrev. Journal, vol., no., pp., month year, doi.

[1] Y. LeCun, Y. Bengio, and G. Hinton, "Deep learning," Nature, vol. 521, no. 7553, pp. 436–444, May 2015, doi: 10.1038/nature14539.

[2] K. He, X. Zhang, S. Ren, and J. Sun, "Deep residual learning for image recognition," in Proc. IEEE Conf. Comput. Vis. Pattern Recognit. (CVPR), 2016, pp. 770–778, doi: 10.1109/CVPR.2016.90.

  • List all authors up to six. With more than six, give the first author and "et al." [9].
  • Abbreviate journal names using the IEEE list and months of five or more letters (Sep., Oct.; May stays May) [9].
  • Reuse the same number every time you cite a source: "LeCun et al. [1] showed..."

How do you cite a research paper in Vancouver style?

Vancouver is the numbered style used in most medical journals, based on the NLM's Citing Medicine and the ICMJE recommendations [10]. Surnames come with initials and no periods, and the journal name is abbreviated.

  1. LeCun Y, Bengio Y, Hinton G. Deep learning. Nature. 2015 May 28;521(7553):436-44. doi: 10.1038/nature14539

  2. Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ. 2021 Mar 29;372:n71. doi: 10.1136/bmj.n71

List the first six authors, then "et al." [10]. In the text, use the number in parentheses or as a superscript, as the journal prefers. Many journals drop the month and day; follow the journal's instructions.

In-text citation rules at a glance

The most common question is when to switch to "et al.". Use this table for papers with one, two and three or more authors.

Style1 author2 authors3 or more authors
APA 7 [4](Surname, 2020)(Mueller & Oppenheimer, 2014)(LeCun et al., 2015)
MLA 9 [6](Surname 45)(Mueller and Oppenheimer 1162)(LeCun et al. 437)
Chicago 18 author-date [8](Surname 2020, 45)(Mueller and Oppenheimer 2014, 1162)(LeCun et al. 2015, 437)
IEEE [9][1][1][1]
Vancouver [10](1)(1)(1)

The one-author column is a pattern, not a real paper. The two-author examples cite Mueller and Oppenheimer (2014) [13].

How to cite a paper with a DOI in five steps

  1. Find the DOI on the article page or the first page of the PDF.
  2. Resolve it. Paste it after https://doi.org/ in your browser. If it opens a different article, the DOI is wrong.
  3. Pull the metadata by pasting the DOI into a citation generator, or from Crossref search.
  4. Check it against the article page: authors, year, volume, issue, pages and capitalization. Publisher data has errors.
  5. Format it in your style and write the DOI the way that style wants it.

Common citation mistakes in research papers

  • Retyped DOIs. One transposed digit breaks the link. Copy and paste, then click it.
  • "et al." in the wrong place. APA reference lists spell out up to 20 authors; et al. belongs in the text.
  • Title case where sentence case belongs. APA and IEEE use sentence case for article titles; MLA and Chicago use title case.
  • Mixing styles, such as APA references with MLA in-text citations.
  • Citations that do not exist. Chatbots can write references from memory. One study found 55% of GPT-3.5 references and 18% of GPT-4 references were fabricated [14]. Check every one.

How to cite a research paper in AI for Research

  1. Free citation generator (0 credits). Paste a DOI, a paper title or keywords into the citation generator, or fill in a website or book by hand. Pick APA, MLA, Chicago, Harvard, IEEE, Vancouver or one of 10,000+ styles, and copy the reference and the in-text citation. See the list of citation styles.
  2. Cite while you write (0 credits). In the editor, type @ to search 250M+ scholarly works and your Library, and insert the citation with its metadata. Switch the document's style once and every citation and the reference list update.
  3. Check your reference list (0 credits). The citation checker confirms each reference exists (Crossref by DOI, OpenAlex by title) and flags retractions, corrections, expressions of concern, preprints, and wrong years or authors. An optional AI check of whether each citing sentence matches the paper's abstract costs 2 credits.
  4. Export to Word, PDF or LaTeX with the reference list in place. See Word and LaTeX export.

Citations, search and exports are free on every plan; the free plan also includes 45 credits a month for AI jobs. See pricing. Limits: a generator can only be as accurate as the publisher's metadata, so still check names and pages, and no tool can tell you whether the paper supports your sentence. That needs you to read it.

FAQ

How do you cite a research paper in APA?

Give surnames and initials, the year in parentheses, the title in sentence case, the journal and volume in italics, the issue in parentheses, the pages, and the DOI as an https://doi.org/ link. Example: LeCun, Y., Bengio, Y., & Hinton, G. (2015). Deep learning. Nature, 521(7553), 436–444. In the text, write (LeCun et al., 2015).

How do I cite a paper with a DOI?

Paste the DOI into a citation generator to pull the publisher's metadata, then check authors, year, volume and pages against the article page. APA, MLA and Chicago write the DOI as a link starting https://doi.org/. IEEE and Vancouver write 'doi:' and the number. Copy and paste DOIs: one wrong character breaks the link.

When do you use et al. in a citation?

In the text, APA 7, MLA 9 and Chicago 18 use et al. for three or more authors; Chicago 17 used it from four. Reference lists differ: APA lists up to 20 authors, MLA uses et al. from three, Chicago 18 and IEEE list up to six, and Vancouver lists the first six then et al.

Should I cite the preprint or the published version?

Cite the version you read. If you read the arXiv or PsyArXiv preprint, cite the preprint with its repository and DOI. If a peer-reviewed version has since been published, read it and cite that instead, because results and wording can change between versions. Many supervisors and journals expect the published version wherever one exists.

Do I need to include the issue number?

Yes, whenever the journal has one, in APA 7, MLA 9, Chicago, IEEE and Vancouver. Chicago author-date puts it in parentheses after the volume, as in 521 (7553). Some online-only journals have no issue, or use an article number instead of pages; then follow your style's article number rule.

Next steps

Sources

  1. APA Style. Journal article references. https://apastyle.apa.org/style-grammar-guidelines/references/examples/journal-article-references
  2. APA Style. Preprint article references. https://apastyle.apa.org/style-grammar-guidelines/references/examples/preprint-article-references
  3. APA Style. Conference proceeding references. https://apastyle.apa.org/style-grammar-guidelines/references/examples/conference-proceeding-references
  4. APA Style. Author–date citation system. https://apastyle.apa.org/style-grammar-guidelines/citations/basic-principles/author-date
  5. APA Style. DOIs and URLs. https://apastyle.apa.org/style-grammar-guidelines/references/dois-urls
  6. Purdue OWL. MLA in-text citations: the basics. https://owl.purdue.edu/owl/research_and_citation/mla_style/mla_formatting_and_style_guide/mla_in_text_citations_the_basics.html ; MLA Style Center. Works cited: a quick guide. https://style.mla.org/works-cited/works-cited-a-quick-guide/
  7. University of Queensland Library. Chicago 18th edition notes and bibliography: journal article. https://guides.library.uq.edu.au/referencing/chicago-18th-edition-notes-and-bibliography/journal-article
  8. Monash University Library. Chicago 18th author-date: journal articles. https://guides.lib.monash.edu/chicago-18-b-author-date/journal-articles
  9. IEEE. IEEE Reference Guide. https://journals.ieeeauthorcenter.ieee.org/wp-content/uploads/sites/7/IEEE_Reference_Guide.pdf
  10. National Library of Medicine. Samples of formatted references for authors of journal articles (ICMJE). https://www.nlm.nih.gov/bsd/uniform_requirements.html ; Patrias K. Citing Medicine. 2nd ed. NLM; 2007. https://www.ncbi.nlm.nih.gov/books/NBK7256/
  11. Crossref. DOI display guidelines. https://www.crossref.org/display-guidelines/
  12. LeCun, Y., Bengio, Y., & Hinton, G. (2015). Deep learning. Nature, 521(7553), 436–444. https://doi.org/10.1038/nature14539
  13. Mueller, P. A., & Oppenheimer, D. M. (2014). The pen is mightier than the keyboard: Advantages of longhand over laptop note taking. Psychological Science, 25(6), 1159–1168. https://doi.org/10.1177/0956797614524581
  14. Walters, W. H., & Wilder, E. I. (2023). Fabrication and errors in the bibliographic citations generated by ChatGPT. Scientific Reports, 13(1), Article 14045. https://doi.org/10.1038/s41598-023-41032-5
  15. Page, M. J., et al. (2021). The PRISMA 2020 statement: An updated guideline for reporting systematic reviews. BMJ, 372, Article n71. https://doi.org/10.1136/bmj.n71

Try it in AI for Research

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