Citing Sources

Citing your sources is an essential part of academic writing. It fulfills several key purposes:

• Gives credit to original authors for their ideas, words, or research
• Supports your arguments with credible, verifiable evidence
• Allows readers to identify and find your sources
• Demonstrates academic honesty and helps avoid plagiarism

Failure to cite sources properly may lead to academic penalties including accusations of plagiarism.

You must cite a source whenever you:

• Use direct quotations, regardless of length
• Paraphrase or summarize another person’s ideas
• Mention theories, concepts, or research that originated elsewhere
• Refer to data or statistics that you didn’t collect yourself
• Use visuals such as photos, artwork, or graphs
• Incorporate your own previous work

You do not need to cite:

• Your own original ideas or thoughts
• Your own data and experiments
• Common knowledge, such as widely known facts or easily observable truths (Example: “The Earth revolves around the sun.”)

If you're unsure whether something is common knowledge, cite it to be safe.

Citations must appear in the following places:

• In-text citation: Brief information (e.g., author and date) placed within the paragraph or slide where the source is used.
• Footnotes or endnotes (used in some styles such as Chicago Notes & Bibliography): Source details placed at the bottom of the page or the end of the document.
• References list / Works Cited / Bibliography: A complete list of all sources cited in your work, located at the end of the paper or presentation.

The format and placement of citations depend on the citation style used.

Written publications such as books and articles are the most commonly cited types of sources, but citations are required for many other types of sources as well. Here are some examples of the different types of sources that you should provide citations for:

• Books and book chapters
• Journal, newspaper, or magazine articles
• Dissertations and theses
• Web pages or online content
• Social media posts
• Films, interviews, podcasts, and other media
• Datasets, maps, images, graphs
• Software and code
• Conference papers and presentations
• Government documents
• Court cases, statutes, laws
• Unpublished / archival materials
• Personal conversations

You need to provide enough information for your reader to easily find your sources. Citation details vary by source type but generally include:

For all sources:

• Author(s) or editor(s)
• Title of the work or article
• Title of the publication (book, journal, website)
• Year of publication

Additional details may include:

• Publisher and place of publication (for books)
• Volume and issue (for journals)
• Page numbers
• URL or DOI (for online sources) - see also What Is a DOI?

Always consult your instructor to confirm which style and edition to use.

The appropriate citation style depends on:

• What style is most used in the academic discipline for which you are writing
• Your instructor’s preferences
• The style guide used by a department, publisher, or journal

There are many different kinds of style guides, but three of the most commonly used are:

• Publication Manual of the American Psychological Association (APA Style)
• The Chicago Manual of Style (Chicago Style)
• MLA Handbook for Writers of Research Papers (MLA Style)

There are also styles created by scholarly or professional associations for specific fields — such as the American Sociological Association or the American Chemical Society or the Associated Press — with publication guidelines especially adapted to their particular disciplines.

See the tabs on the left to explore more about each of these different styles.

Just need to create a quick bibliography? Many library databases (including the library catalog) include a “Cite” option to create a citation for sources you locate in different styles.

Although citation generators are useful for saving time and gathering information quickly, they are not 100% accurate. Formatting errors occur often, so always double-check automatically generated citations using the appropriate style guide.

Common citation generator errors:

• Incorrect capitalization
• Missing punctuation
• Incomplete author or date information
• Formatting inconsistencies (italics, quotation marks, indents, etc.)

A citation manager such as EndNote or Zotero is a software tool that helps you collect, organize, and cite sources for your research and writing. Citation managers allow you to automatically create in-text citations, footnotes, and bibliographies in any style that you prefer, such as APA, MLA, Chicago, and more.

See Citation Management Software for more information and helpful resources.

Here are some best practices to keep in mind:

• Start keeping track of sources early in your research process.
• Stay consistent with your chosen citation style.
• Consult style guides and citation manuals when unsure.
• When in doubt, it is better to overcite than undercite.
• Ask a librarian, instructor, or writing center consultant if you need help.