Citation styles compared: Harvard, Vancouver, Chicago, MLA

Which citation style should you use?

You rarely get to choose. For a thesis, your university’s thesis guidelines or your department decides. Some Indian universities name one style for every discipline; others leave it to the department, and many simply say “a standard style, used consistently”. For a journal paper, the journal’s author guidelines decide, and they often modify a standard style.

If the thesis rules leave it open, use the style most common in the journals you read. Examiners in your field will find it familiar, and your papers and thesis can share one reference library. Whatever you choose, mention it in the thesis front matter or methodology if your university asks you to, and use it without mixing.

How do the styles compare side by side?

The tables below use one real journal article, Braun and Clarke’s 2006 paper on thematic analysis, so you can see the differences directly. Page 79 is used as an example quotation page.

Look at what changes. Author names: initials after the surname (Harvard, APA, Vancouver), full first names (Chicago, MLA), or initials first (IEEE). Article titles: sentence case (Harvard, APA, Vancouver, IEEE) or title case (Chicago, MLA). Quotation marks around the article title in some styles, none in others. Journal names in full or abbreviated. Small things, but a reference list with mixed conventions is the first thing an examiner notices.

Harvard and Vancouver: what to watch for

Harvard

“Harvard” is a family of author-date styles, not one style. There is no Harvard manual. Universities and publishers each have their own version, and they differ in punctuation, in whether “p.” is used, in how many authors are listed before “et al.”, and in how online sources are written. Cite Them Right, published in the UK and used by many universities there, is the version most scholars mean. If your university’s guidelines include a Harvard example, follow that example exactly, even where it differs from Cite Them Right.

Two points catch scholars out. First, “Harvard” and APA look similar, and many theses end up mixing them: “and” in one citation and “&” in the next, “p.” in some and not others. Pick one and check. Second, in the reference list, Harvard variants usually put the year in round brackets straight after the authors with no full stop after it, where APA has one: “(2006) ‘Using…’” rather than “(2006). Using…”.

Vancouver

Vancouver is the numbered style used by most medical and health science journals, based on the ICMJE recommendations and the National Library of Medicine’s Citing Medicine. Sources are numbered in the order you first cite them, and the reference list follows that order, not the alphabet.

• Numbers in the text go in square brackets, round brackets or superscript, depending on the journal. Check the target journal and apply one form throughout.
• Author names are surname plus initials with no full stops or spaces: “Braun V, Clarke V”. Many journals list the first six authors, then “et al.”
• Journal titles are abbreviated in NLM form (“Qual Res Psychol”). The NLM Catalog gives the official abbreviation for journals indexed there.
• Punctuation is sparse: year, volume, issue and pages run together as 2006;3(2):77-101.

Chicago and MLA: what to watch for

Chicago has two systems

The Chicago Manual of Style offers two separate systems. Do not mix them.

Author-date works like Harvard or APA: (Braun and Clarke 2006, 79) in the text, with no comma between author and year and no “p.” before the page. The reference list puts the year straight after the authors.

Notes and bibliography is the traditional humanities system. A superscript number in the text points to a footnote or endnote. The first note for a source gives full details; later notes use a short form:

• First note: 1. Virginia Braun and Victoria Clarke, “Using Thematic Analysis in Psychology,” Qualitative Research in Psychology 3, no. 2 (2006): 79, https://doi.org/10.1191/1478088706qp063oa.
• Later note: 4. Braun and Clarke, “Using Thematic Analysis,” 82.

Chicago now prefers these short notes to “ibid.”. A bibliography at the end lists sources alphabetically. Some universities drop the bibliography when full notes are given; check your guidelines. In Word, use the built-in footnote tool rather than typing superscript numbers, or renumbering will break.

MLA

MLA is built for literature and language studies, where the page you are discussing matters more than the year. The in-text citation is the author and page with no comma: (Braun and Clarke 79). If you name the author in your sentence, only the page goes in brackets. The list is called “Works Cited”.

MLA 9 builds each entry from “core elements” in a fixed order: author, title of source, title of container (the journal or book), other contributors, version, number, publisher, date, location (pages, DOI or URL). Once you understand containers, unusual sources such as a poem in an anthology or an episode on a streaming service become straightforward. For three or more authors, MLA gives the first author followed by “et al.”, both in the text and in Works Cited.

When you quote a primary literary text often, MLA allows abbreviated titles and line or chapter numbers instead of pages. Your supervisor may have a department custom for editions of classic texts; follow it and state the edition once.

APA 7 and IEEE in brief

APA 7 is an author-date style used across psychology, education, management and many social sciences. In the text: (Braun & Clarke, 2006), with “et al.” from three authors onwards. The reference list is alphabetical, with the year in brackets after the authors, sentence-case article titles and the DOI as a full URL. APA also sets rules for headings, tables and figures that matter in a thesis. See the APA 7 guide for those and for reference examples by source type.

IEEE is a numbered style used in engineering and computer science. Numbers in square brackets are assigned in order of first citation, the list follows that order, authors appear as initials then surname, and journal titles are abbreviated using IEEE’s list. The IEEE guide covers conference papers, standards, patents and equations.

How do you switch from one citation style to another?

This happens more often than scholars expect: a paper rejected by an IEEE journal goes to an Elsevier journal with its own numbered style, or a thesis chapter written in APA must be turned into Harvard because the university format says so.

If you inserted citations with a reference manager, switching is quick. In Zotero or Mendeley, choose the new style from the style list and refresh. Both use Citation Style Language (CSL) files, and styles exist for most journals and many universities. Our Zotero vs Mendeley guide covers setting this up.

If citations were typed by hand, you have two options: rebuild them in a reference manager (a day or two for a thesis, and worth it), or convert by hand very carefully. For a thesis with 200 or more references, rebuilding is almost always faster and safer.

Either way, the automated result is not the end. Reference managers only format what is in their database, and the database is often wrong: titles in capitals, missing issue numbers, conference papers stored as journal articles. After switching, run through this list:

• Every in-text citation changed format, including ones typed by hand rather than inserted by the reference manager.
• Numbered styles: the numbers run in order of first citation, and a source cited again keeps its first number.
• Author-date styles: the list is alphabetical, and an author with two works from one year gets 2021a and 2021b.
• Phrases like “as shown in [4]” were rewritten if you moved to author-date, and “Sharma (2020) found” was rewritten if you moved to numbers.
• Journal names are abbreviated (Vancouver, IEEE) or written in full (Harvard, APA, Chicago, MLA) as the style requires.
• DOIs appear in the format the style uses, and none are broken across lines in a way that changes them.
• Your university’s thesis rules, where they differ from the published style, have been applied last.

Correct citation is also part of academic integrity. A source cited in the wrong format is a formatting error; a source you used but did not cite is a different matter. The paraphrasing guide covers when a citation is needed.