Every thesis writer hits the question early on: which citation style do I use? The answer is in your department’s style guide — and if not there, in your discipline’s convention. This post puts the five major citation styles side by side, shows how an in-text reference and a bibliography entry look in each, and flags the typical pitfalls when switching styles.
The five major styles at a glance
Before you get lost in detail: there are two basic types. Author-date styles (APA, MLA, Chicago author-date, Harvard) cite in the running text with name and year. Numeric styles (Vancouver, IEEE) cite with a running number that points to the bibliography. Chicago can do both — depending on the variant.
| Style | System | Main use | Typical in-text reference |
|---|---|---|---|
| APA 7 | Author-date (parenthetical) | Psychology, education, social sciences | (Mueller, 2023, p. 42) |
| MLA 9 | Author-page (parenthetical) | English, literary studies, humanities | (Mueller 42) |
| Chicago 17 (Notes) | Footnotes | History, theology, philosophy | Superscript + footnote |
| Chicago 17 (Author-Date) | Author-date (parenthetical) | Natural sciences (US tradition) | (Mueller 2023, 42) |
| Vancouver | Numeric | Medicine, life sciences | (1) or ¹ |
| IEEE | Numeric | Electrical engineering, computer science | [1] |
This table is the short version. The details — where the comma goes, when “et al.” kicks in, how an online source looks — decide the impression your thesis makes when read closely.
APA 7 — the standard in psychology and social sciences
APA (American Psychological Association) reached its 7th edition in 2019. It’s the standard in psychology, education, social work, and many business programmes.
In-text:
Trust is the precondition for openness (Mueller, 2023, p. 42).
For narrative integration, the year goes in brackets after the name: Mueller (2023, p. 42) describes …
Reference list (book):
Mueller, H. (2023). Qualitative methods in social research (3rd ed.). Beltz Juventa.
Reference list (journal article):
Weber, K., & Braun, S. (2022). Trust constructs in qualitative interviews. Journal of Sociology, 51(3), 211–229. https://doi.org/10.1515/jsoc-2022-0014
Common APA mistakes: missing DOI, wrong italics (only the book or journal title is italicised, not the article title), “et al.” used too early (APA 7 starts at three authors, not two). For a full walkthrough, see the APA 7 guide.
MLA 9 — the style of English studies
MLA (Modern Language Association) is the standard in English, comparative literature, and large parts of the humanities. The logic differs from APA: no year in the in-text reference, just a page number.
In-text:
Trust is the precondition for openness (Mueller 42).
No comma between name and page number. The year only appears in the bibliography — which means that if you cite multiple works by the same author, you need to add a shortened title in the text: (Mueller, Qualitative 42).
Works Cited (book):
Mueller, Hans. Qualitative Methods in Social Research. 3rd ed., Beltz Juventa, 2023.
Works Cited (journal article):
Weber, Klara, and Sophie Braun. “Trust Constructs in Qualitative Interviews.” Journal of Sociology, vol. 51, no. 3, 2022, pp. 211–29.
MLA has a quirk: the bibliography is called “Works Cited” and contains only sources actually cited in the text — no further reading, no background literature. Anything that doesn’t have an in-text reference doesn’t belong there.
Chicago 17 — the style of the humanities
The Chicago Manual of Style comes in two flavours: Notes and Bibliography (with footnotes, classic in history, philosophy, theology) and Author-Date (an author-date system, more common in US-tradition natural sciences).
Chicago Notes — footnote (first citation, full note):
¹ Hans Mueller, Qualitative Methods in Social Research, 3rd ed. (Weinheim: Beltz Juventa, 2023), 42.
Chicago Notes — footnote (subsequent citation, short note):
² Mueller, Qualitative Methods, 47.
Bibliography:
Mueller, Hans. Qualitative Methods in Social Research. 3rd ed. Weinheim: Beltz Juventa, 2023.
Chicago Notes is often confused with the German footnote tradition. In fact, the differences in punctuation (comma vs. period, brackets around publisher and year) are small but consistent. If your department asks for “Chicago”, confirm: notes or author-date?
Vancouver — the standard in medicine and life sciences
Vancouver is a numeric style used across medicine, life sciences, and many clinical disciplines. Sources are numbered in order of first mention.
In-text:
Trust is a precondition for openness in qualitative interviews (1).
Some variants use square brackets, some round, some superscript. Which one applies depends on the journal or department style sheet.
Reference list (journal article):
- Weber K, Braun S. Trust constructs in qualitative interviews. J Sociol. 2022;51(3):211–29.
Vancouver shortens first names to initials with no periods (Weber K, not Weber, K.) and abbreviates journal titles per the NLM list. Writing out “Journal of Sociology” instead of “J Sociol” signals you haven’t read the style.
A Vancouver pitfall: when you cite a source again, it keeps the number it was first assigned. You refer to the same numeral every time — you don’t generate a new one.
IEEE — the style of engineering and computer science
IEEE (Institute of Electrical and Electronics Engineers) is the standard across electrical engineering, computer science, communications, and many engineering programmes. Like Vancouver, it’s numeric — but the formatting differs.
In-text:
Trust is a precondition for openness in qualitative interviews [1].
Square brackets, in normal position (not superscript). Multiple sources: [1], [3], [5] or compactly [1]–[3].
Reference list (conference paper):
[1] K. Weber and S. Braun, “Trust constructs in qualitative interviews,” in Proc. 14th Int. Conf. on Qualitative Research, Berlin, Germany, 2022, pp. 211–229, doi: 10.1109/ICQR.2022.0014.
IEEE has its own conventions for first names (initials with periods: K. Weber), conference names (mandatory: location, country, year), and online sources (“[Online]. Available: URL”). Anyone coming to IEEE from an APA background almost always misses these on the first pass.
The same source in five styles
To make the difference tangible, here’s the same source — a journal article by Weber and Braun (2022) on trust in qualitative interviews — rendered in all five styles:
APA 7:
Weber, K., & Braun, S. (2022). Trust constructs in qualitative interviews. Journal of Sociology, 51(3), 211–229. https://doi.org/10.1515/jsoc-2022-0014
MLA 9:
Weber, Klara, and Sophie Braun. “Trust Constructs in Qualitative Interviews.” Journal of Sociology, vol. 51, no. 3, 2022, pp. 211–29.
Chicago (Author-Date):
Weber, Klara, and Sophie Braun. 2022. “Trust Constructs in Qualitative Interviews.” Journal of Sociology 51 (3): 211–229.
Vancouver:
- Weber K, Braun S. Trust constructs in qualitative interviews. J Sociol. 2022;51(3):211–29.
IEEE:
[1] K. Weber and S. Braun, “Trust constructs in qualitative interviews,” J. Sociol., vol. 51, no. 3, pp. 211–229, 2022.
Same source, five versions. With Zotero you flip between them in one click — if you’re typing by hand, don’t switch styles late in the writing process.
Switching styles: what goes wrong
It happens more often than you’d think: you write half the thesis in APA and then learn your department wants Chicago. Or your second examiner insists on Vancouver. With a reference manager (Zotero, Mendeley, EndNote), the switch is a button press — but watch out:
- Special characters. Quotation marks, hyphens, and apostrophes are set differently per style. The automated conversion routinely misses them.
- “Et al.” threshold. APA 7 uses “et al.” starting with three authors, MLA from three, Vancouver not at all (list every author), IEEE after six. Skip the check and you’ll have an “et al.” in the text that doesn’t resolve in the bibliography.
- Page-number format. “211–229” or “211–29”? Hyphen or en-dash? Style-dependent.
- DOI / URL. APA 7 wants the DOI as a URL (https://doi.org/…), IEEE wants “doi: 10.xxxx/xxxxx”, Vancouver often skips it entirely. Conversions produce mixed forms here with great consistency.
If you switch styles, plan half a day for manual cleanup. And ask the most important question upfront: which style does my department want? The answer is usually in the thesis guidelines — and if not, ask in office hours.
How Acurio works with any style
Acurio doesn’t check the format of your references. Acurio checks whether the claim in your text is actually supported by the source you cite. That’s the difference between a formatting error (wrong bracket in APA) and a substantive error (the source says something different from what you claim).
It doesn’t matter whether you use APA, MLA, Chicago, Vancouver, or IEEE — Acurio reads your sources alongside your text and cross-checks your claims. If you want to check your bachelor’s or master’s thesis before submission, try Acurio for free.
Pre-submission checklist
- Style confirmed? One look at the guidelines, ideally two.
- Consistency? No mixing of two styles — not even “just once”.
- “Et al.” threshold respected? Check style-by-style.
- Bibliography complete? Every source cited appears in the bibliography, every bibliography entry appears in the text.
- Content accurate? The source really says what you claim. No format check helps here — only a real citation check.
The citation style is a convention, not a quality marker. Pick the right one for your discipline, stick with it, and focus on what actually matters: that your sources hold up what you attribute to them.