Citation styles: APA, IEEE, Harvard

To cite in APA style, you put the author’s surname and the year of publication in the text, for example (Author, 2024) or Author (2024), and give the full details in a reference list sorted alphabetically by author. IEEE works differently, with numbers in square brackets such as [1] in order of first citation. Harvard is an author-date family similar to APA but without one official manual. Which style you use is decided by your department, supervisor or journal.

The three styles at a glance

	APA	IEEE	Harvard
Type	Author-date	Numeric	Author-date
In-text example	(Author, 2024, p. 12)	[1] or [1, p. 12]	(Author 2024, p. 12)
Reference list order	Alphabetical by author	Numerical by first citation	Alphabetical by author
Defined by	American Psychological Association	IEEE	No single authority; institutional guides
Common in	Psychology, education, social sciences, nursing	Engineering, computer science, physics	Business, humanities, many UK universities

APA: 7th edition is the widely used standard at the time of writing. Check the official guides for updates.

How to cite in APA

In the text:

• One author: (Author, 2024) or Author (2024) found that …
• Two authors: (Author & Author, 2024)
• Three or more authors: (Author et al., 2024)
• Direct quotes always include a page or other locator: (Author, 2024, p. 12)

In the reference list:

• Journal article: Author, A. A., & Author, B. B. (Year). Title of the article in sentence case. Journal Name, Volume(Issue), pages. https://doi.org/…
• Book: Author, A. A. (Year). Title of the book in sentence case (Edition). Publisher.
• Web page: Author or Organisation. (Year, Month Day). Title of page. Site Name. URL

The official APA Style website has examples for many more source types.

How to cite in IEEE

In the text: sources are numbered in the order you first cite them. Reuse the same number every time the source appears: “as shown in [2]”, “several studies [3]–[5]”.

In the reference list:

• Journal article: [1] A. Author and B. Author, “Title of article,” Abbrev. Journal Name, vol. X, no. X, pp. XX–XX, Month Year, doi: …
• Book: [2] A. Author, Title of Book, Xth ed. City, Country: Publisher, Year.
• Conference paper: [3] A. Author, “Title of paper,” in Proc. Name of Conference, City, Year, pp. XX–XX.

IEEE publishes a reference guide for authors on its website; journals may add their own details.

How to cite in Harvard

Harvard is not one style but a family. The basic pattern is (Author Year, page) in the text and an alphabetical reference list:

• Author, A. (Year) Title of book. Edition. Place: Publisher.
• Author, A. and Author, B. (Year) ‘Title of article’, Journal Name, Volume(Issue), pp. XX–XX.

Punctuation, the use of “and” or “&” and the treatment of online sources vary between universities. Use your institution’s Harvard guide, often available from the library.

Other styles you may meet

• Chicago: two systems, notes and bibliography (common in history and the humanities) and author-date.
• MLA: author-page style used in literature and languages.
• Vancouver: numeric style used widely in medicine.
• OSCOLA: footnote style for law in the UK.

Quoting or paraphrasing?

Whatever the style, you either quote or paraphrase. A direct quote reproduces the exact wording in quotation marks with a page number; omissions are marked with an ellipsis. A paraphrase restates an idea in your own words and still needs a citation. In most fields, paraphrase dominates and direct quotes are kept for definitions or wording you analyse.

How to stay consistent

1. Confirm the style and edition or variant with your department or the journal’s author guidelines.
2. Use a reference manager and select the exact style; Zotero and Mendeley use the Citation Style Language with thousands of styles.
3. Check imported data. Missing issue numbers, wrong capitalisation or incomplete author names come from the source data, not the style.
4. Proofread the final list against a few official examples.

Checklist before submission

• One style used throughout, including tables and figures.
• Every in-text citation appears in the reference list, and vice versa.
• Direct quotes have page numbers or other locators.
• DOIs included where available.
• Author names, years and titles match between text and list.
• Secondary citations are marked, and used only when the original is unavailable.

Note: correct citation is also your protection against plagiarism concerns. Missing quotation marks and incomplete references are among the most common reasons for matches in a plagiarism check.

Citations shape every chapter, especially the literature review. For the overall order of chapters, see thesis structure. More guides are in the writing section.