How to Cite an Encyclopedia or Wikipedia Article

Britannica, the Stanford Encyclopedia of Philosophy and other encyclopedias.

For a word in a dictionary, use Dictionary Entry, and to cite a whole encyclopedia or other reference book, use Book.

What You'll Need

Entry Title
Short title
Author(s)
Encyclopedia
Editor(s)
Edition
Publisher
Date Published
Pages
URL
Date Accessed

Take the entry’s title, and its author if it names one, from the article, and the editors, edition and publisher from the encyclopedia’s title page or about page. Online, link to a fixed version if there is one, such as a Wikipedia permanent link or an archived edition of the Stanford Encyclopedia of Philosophy, and give its date. There is no box for a volume, so add one by hand if your style asks for it.

Example Citations

APA 7th edition
Ismael, J. (2025). Quantum mechanics. In E. N. Zalta & U. Nodelman (Eds.), The Stanford Encyclopedia of Philosophy (Spring 2025). Metaphysics Research Lab, Stanford University. https://plato.stanford.edu/archives/spr2025/entries/qm/
In-text (Ismael, 2025)
MLA 9th edition
Ismael, Jenann. “Quantum Mechanics.” The Stanford Encyclopedia of Philosophy, edited by Edward N. Zalta and Uri Nodelman, Spring 2025, Metaphysics Research Lab, Stanford University, 2025, plato.stanford.edu/archives/spr2025/entries/qm/.
In-text (Ismael)
Chicago 18th edition (notes and bibliography)
Ismael, Jenann. “Quantum Mechanics.” In The Stanford Encyclopedia of Philosophy, Spring 2025, edited by Edward N. Zalta and Uri Nodelman. Metaphysics Research Lab, Stanford University, 2025. https://plato.stanford.edu/archives/spr2025/entries/qm/.
Footnote Jenann Ismael, “Quantum Mechanics,” in The Stanford Encyclopedia of Philosophy, Spring 2025, ed. Edward N. Zalta and Uri Nodelman (Metaphysics Research Lab, Stanford University, 2025), https://plato.stanford.edu/archives/spr2025/entries/qm/.
Harvard (Cite Them Right 12th edition)
Ismael, J. (2025) ‘Quantum mechanics’, The Stanford Encyclopedia of Philosophy. Spring 2025. Edited by E.N. Zalta and U. Nodelman. Metaphysics Research Lab, Stanford University. Available at: https://plato.stanford.edu/archives/spr2025/entries/qm/ (Accessed: 18 October 2026).
In-text (Ismael, 2025)
IEEE
[1]
J. Ismael, “Quantum Mechanics,” The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University, 2025. Accessed: Oct. 18, 2026. [Online]. Available: https://plato.stanford.edu/archives/spr2025/entries/qm/
In-text [1]

Numbered by order of appearance in your document.

Vancouver
1.
Ismael J. Quantum mechanics. In: Zalta EN, Nodelman U, editors. The Stanford Encyclopedia of Philosophy [Internet]. Spring 2025. Metaphysics Research Lab, Stanford University; 2025 [cited 2026 Oct 18]. Available from: https://plato.stanford.edu/archives/spr2025/entries/qm/
In-text (1)

Numbered by order of appearance in your document.

How to Cite Wikipedia

Choose Encyclopedia Entry for a Wikipedia article or any other wiki page. Type Wikipedia as the encyclopedia and the title as Wikipedia shows it. The article has no author, so leave Author(s) empty.

  • URL: the permanent link to the version you read, as APA asks. Choose Permanent link in the Tools menu, or pick the version’s date and time in View history.
  • Date Published: the date of that version, as View history shows it.
  • Publisher: Chicago’s Wikipedia example names the Wikimedia Foundation. APA’s names none, so leave it empty for APA.
  • APA date: we print the year only. APA’s example gives the full date, (2019, December 8), so add the month and day by hand.

Chicago normally cites well-known online encyclopedias in the notes only, and here an entry with no author, such as a Wikipedia article, gets a note and no bibliography entry. Chicago’s own Wikipedia example is set as a web page instead: its note gives the time the page was last modified, as in “last modified December 19, 2023, 21:54 (UTC)”, and its bibliography lists the page under Wikimedia Foundation. Follow it by hand if you need a bibliography entry.

APA calls Wikipedia a secondary source and suggests students ask their teacher whether it is a suitable source. Chicago calls it a tertiary source and points you to the sources its articles cite.

Other Source Types

Website Book Journal Article Newspaper Article Book Chapter Thesis/Dissertation Report Video Podcast/Broadcast Magazine Article Software Dataset Patent Legal Case Legislation Bill Regulation Hearing Standard Treaty Conference Paper Manuscript Review Book Review Classic Work Reference Entry Dictionary Entry Periodical Collection Interview Speech Song Musical Score Graphic Figure Map Performance Event Pamphlet Preprint Document Post Blog Post Personal Communication Generative AI