Citing sources correctly is one of the foundational skills of academic writing — and one of the most common causes of lost marks or even plagiarism accusations. This guide covers the three most widely used citation systems: APA 7th edition (social sciences), MLA 9th edition (humanities), and Chicago (history and arts). You'll find in-text formats, reference list examples for books, journal articles, and websites, plus tips to avoid accidental plagiarism. For context, see our Academic English Complete Guide.
🎯 1. Why We Cite Sources
Citation is not just a formality — it serves four essential purposes in academic writing:
Purpose
What it does
Gives credit
Acknowledges the intellectual work of others. Failing to do so is plagiarism.
Builds credibility
Shows your reader that your argument is grounded in authoritative sources.
Allows verification
Enables readers to find and check the sources you used.
Joins the conversation
Positions your work within an existing academic debate.
💡 Rule of thumb: If you didn't know the information before you read it, cite it — whether you're quoting, paraphrasing, or summarising.
🧭 2. Choosing the Right Style
Different disciplines use different citation systems. The choice is not arbitrary — each style evolved to serve the needs of its field.
🔵 APA 7th ed.
Social Sciences · Psychology · Education · Business · Nursing
Uses author–date in-text citations. Emphasises currency of research, which is critical in fast-moving fields.
In-text: (Smith, 2020, p. 15) Reference: Smith, J. (2020). Title of work. Publisher.
🟢 MLA 9th ed.
Literature · Languages · Arts · Cultural Studies
Uses author–page in-text citations. Focuses on close reading of texts, where page numbers matter more than publication dates.
In-text: (Smith 15) Works Cited: Smith, John. Title of Work. Publisher, 2020.
🔴 Chicago 17th ed.
History · Philosophy · Theology · Some Humanities
Uses footnotes or endnotes plus a bibliography. Ideal for historical narrative where long citations interrupt the flow.
Footnote: 1. John Smith, Title of Work (Publisher, 2020), 15. Bibliography: Smith, John. Title of Work. Publisher, 2020.
🔵 3. APA 7th Edition (Social Sciences)
The American Psychological Association (APA) style is used across the social sciences. The 7th edition (2019) is the current standard.
In-Text Citations
APA uses the author–date format. Page numbers are required for direct quotes but optional for paraphrases.
Paraphrase: Smith (2020) argued that...
Paraphrase (parenthetical): ...as several studies have shown (Smith, 2020).
Direct quote: "The evidence was overwhelming" (Smith, 2020, p. 15).
Two authors: (Smith & Lee, 2020)
Three or more authors: (Smith et al., 2020)
Same author, same year: (Smith, 2020a, 2020b)
Reference List Entries
The reference list appears at the end of the paper, alphabetised by author surname, with a hanging indent.
Book:
Smith, J. (2020). Title of work: Subtitle in sentence case. Publisher.
Journal article with DOI:
Lee, K., & Karim, A. (2019). Title of article in sentence case. Journal Name, 12(3), 45–67. https://doi.org/10.1234/example
Website:
World Health Organization. (2024, March 15). Title of page. https://www.who.int/example
Chapter in edited book:
Brown, P. (2021). Title of chapter. In R. Green (Ed.), Title of book (pp. 25–48). Publisher.
Newspaper article:
Johnson, M. (2023, September 12). Title of article. The Guardian. https://www.theguardian.com/example
💡 APA 7 changes: Publisher location is no longer required (only publisher name). "Retrieved from" is removed before URLs. Up to 20 authors are listed before using "et al."
🟢 4. MLA 9th Edition (Humanities)
The Modern Language Association (MLA) style is standard in literature, languages, and cultural studies. The 9th edition (2021) emphasises a universal set of "core elements" for any source type.
In-Text Citations
MLA uses the author–page format (no year, no "p." before the page number).
Paraphrase: Smith argues that...
Paraphrase (parenthetical): ...as critics have observed (Smith 15).
Direct quote: "The evidence was overwhelming" (Smith 15).
Two authors: (Smith and Lee 15)
Three or more authors: (Smith et al. 15)
Same author, multiple works: (Smith, Another Book 15)
Works Cited Entries
The list is titled "Works Cited" (not "References"), alphabetised by author surname, with a hanging indent.
Book:
Smith, John. Title of Work: Subtitle. Publisher, 2020.
Journal article:
Lee, Karen. "Title of Article." Journal Name, vol. 12, no. 3, 2019, pp. 45–67.
Website:
"Title of Web Page." Website Name, 15 Mar. 2024, www.example.com/page.
Chapter in edited book:
Brown, Peter. "Title of Chapter." Title of Book, edited by Rachel Green, Publisher, 2021, pp. 25–48.
Newspaper article:
Johnson, Mark. "Title of Article." The Guardian, 12 Sept. 2023, www.theguardian.com/example.
💡 MLA 9 changes: The 9th edition adopts a unified set of "core elements" — Author. Title of Source. Title of Container. Other Contributors. Version. Number. Publisher. Publication Date. Location. This applies to any source type.
🔴 5. Chicago Style (History & Arts)
The Chicago Manual of Style is used primarily in history, philosophy, and some humanities. It has two variants: Notes & Bibliography (used in humanities) and Author–Date (used in sciences). This guide covers the Notes & Bibliography variant.
Footnote / Endnote Format
In-text, Chicago uses superscript numbers that refer to footnotes (at the bottom of the page) or endnotes (at the end of the paper).
First reference (full):
1. John Smith, Title of Work (New York: Publisher, 2020), 15.
Subsequent reference (short):
2. Smith, Title of Work, 22.
Two authors:
3. John Smith and Karen Lee, Title of Work (Publisher, 2020), 15.
Chapter in edited book:
4. Peter Brown, "Title of Chapter," in Title of Book, ed. Rachel Green (Publisher, 2021), 30.
Bibliography Entries
The bibliography is alphabetised by author surname, with a hanging indent.
Book:
Smith, John. Title of Work. New York: Publisher, 2020.
Journal article:
Lee, Karen. "Title of Article." Journal Name 12, no. 3 (2019): 45–67.
Website:
"Title of Web Page." Website Name. Last modified March 15, 2024. https://www.example.com/page.
Chapter in edited book:
Brown, Peter. "Title of Chapter." In Title of Book, edited by Rachel Green, 25–48. Publisher, 2021.
💡 Chicago vs. APA/MLA: Chicago allows you to include sources you consulted but did not directly cite in the bibliography. APA's reference list and MLA's Works Cited only include cited sources.
📊 6. Side-by-Side Comparison Table
Citation Style Quick Reference
Feature
APA 7th
MLA 9th
Chicago (N&B)
Discipline
Social sciences
Humanities
History, arts
In-text format
(Smith, 2020, p. 15)
(Smith 15)
Footnote1
List title
References
Works Cited
Bibliography
Alphabetical by
Surname
Surname
Surname
Includes uncited sources?
No
No
Yes (bibliography)
Year in-text?
Yes
No
In footnote only
Page number in-text?
Only for quotes
Always
Always (footnote)
Book title capitalisation
Sentence case
Title Case
Title Case
⚠️ 7. Avoiding Plagiarism
Plagiarism is the presentation of someone else's work or ideas as your own. It is treated very seriously in every academic institution. Here are the seven most common forms:
Copy-paste without quotation marks. Even a single sentence copied verbatim must be in quotation marks with a citation.
Patchwriting. Changing a few words while keeping the original sentence structure. This is still plagiarism — you must restructure and reword.
Missing citation for a paraphrase. If you reworded an idea but didn't cite the source, that is still plagiarism.
Self-plagiarism. Reusing your own previous work (e.g. a paper from last semester) without permission or disclosure.
Incorrect citation. Citing the wrong author, year, or page — even accidentally — undermines academic integrity.
Ghost-writing. Submitting a paper written by someone else (or by AI) as your own.
Collaboration without disclosure. Working with peers when the assignment was individual.
💡 Practical strategy: Take notes with the source information attached. When paraphrasing, close the original text and write from memory, then compare. If more than 3–4 consecutive words match, rewrite.
🛠️ 8. Citation Tools & Best Practices
Citation managers save time — but only if you verify their output. Here's a practical comparison:
Tool
Best for
Cost
Watch out for
Zotero
Students, researchers
Free
Occasional errors in web page metadata
Mendeley
PDF annotation + citation
Free
Some citation style templates outdated
EndNote
Large research teams
Paid
Steep learning curve
EasyBib
Quick single citations
Freemium
Ads, aggressive upsells
Purdue OWL
Reference guide (not a generator)
Free
Manual only
Best Practices
Cite as you write — don't leave citations for the end. You will lose track of which source each idea came from.
Keep a running bibliography — add each source the moment you first use it.
Save the DOI or URL for every source, even if you cite only once.
Check against the official manual — not just a generator. Buy or borrow the current edition of your style manual.
Be consistent — mixing APA and MLA in one paper is an automatic red flag.
📥 Free Citation Worksheets
Download the printable PDF with citation templates, matching exercises, and answer keys for APA, MLA, and Chicago.
It depends on your discipline: APA 7th for social sciences, psychology, education, and business; MLA 9th for literature, languages, and arts; Chicago for history, philosophy, and some humanities. Always follow your instructor's or journal's instruction.
Yes. Any idea that is not your own and not common knowledge must be cited, whether you quote it directly or paraphrase it. Only widely known facts (e.g. 'water boils at 100°C') do not require citation.
A reference list (APA) contains only the sources you cited in the text. A bibliography (Chicago) may also include sources you consulted but did not directly cite. MLA uses 'Works Cited', which is equivalent to a reference list.
APA: use the title in place of the author and 'n.d.' for no date — (Title, n.d.). MLA: use a shortened title — ('Short Title' 15). Chicago: use the title in the footnote. Always check your style manual for the exact format.
Yes, but always verify. Tools like Zotero, Mendeley, and EasyBib save time but frequently produce errors (wrong capitalization, missing elements, incorrect italics). Treat generated citations as a first draft only.
Plagiarism includes: copying text without quotation marks, paraphrasing too closely (patchwriting), reusing your own previous work without permission (self-plagiarism), and failing to cite a source. Even accidental plagiarism is penalised.