Appendix C — Citation Styles Side by Side

Quick reference for the four styles in this book: IEEE, APA, Chicago, and ACS. Chapter 11 explains the why; this appendix is the lookup table.

You don't memorize four citation styles. You learn to recognize which one your venue requires, then look up the exact mechanics — or, better, let a reference manager generate them and you verify the output. This appendix gives you the same source rendered all four ways for three common source types, so you can see what changes and what doesn't.

The one rule that beats memorizing any style: be consistent, and follow the target's instructions. A reference list that's flawless APA except for three entries in IEEE looks worse than one that's slightly imperfect but uniform. Pick the style your audience requires, then make every entry match its siblings.

When each field uses which

Style Used by In-text mechanism What it foregrounds
IEEE Engineering, computer science Numbered [1], in order of appearance Whether a claim is supported (clean prose, dense citing)
APA Psychology, social/behavioral sciences, much life science, general Author–date (Author, Year) Who found it and when (situates a contested claim)
Chicago History, humanities, some policy Footnotes ¹ (notes-and-bibliography) or author–date Discursive notes; flexible across fields
ACS Chemistry Numbered, often superscript ¹ Compact citing in equation-dense text

There is no "correct" style — only the one your venue requires, applied uniformly. The choice is really Chapter 2 applied to references: identical content, different audience, completely different surface.

Example 1 — A journal / conference article

The source (a real, Tier 1 paper): Ashish Vaswani, Noam Shazeer, Niki Parmar, Jakob Uszkoreit, Llion Jones, Aidan N. Gomez, Łukasz Kaiser, and Illia Polosukhin, "Attention Is All You Need," presented at NeurIPS 2017.

IEEE  (in-text: …the Transformer architecture [1] removed recurrence.)
[1] A. Vaswani et al., "Attention is all you need," in Proc. 31st Conf.
    Neural Inf. Process. Syst. (NeurIPS), Long Beach, CA, USA, 2017,
    pp. 5998–6008.

APA   (in-text: …removed recurrence (Vaswani et al., 2017).)
Vaswani, A., Shazeer, N., Parmar, N., Uszkoreit, J., Jones, L., Gomez,
    A. N., Kaiser, Ł., & Polosukhin, I. (2017). Attention is all you
    need. Advances in Neural Information Processing Systems, 30.

Chicago  (notes-and-bibliography; in-text: a superscript ¹ at the clause)
1. Ashish Vaswani et al., "Attention Is All You Need" (paper presented
   at the 31st Conference on Neural Information Processing Systems,
   Long Beach, CA, 2017).

ACS   (in-text: a superscript ¹ after the claim)
(1) Vaswani, A.; Shazeer, N.; Parmar, N.; Uszkoreit, J.; Jones, L.;
    Gomez, A. N.; Kaiser, L.; Polosukhin, I. Attention Is All You Need.
    Adv. Neural Inf. Process. Syst. 2017, 30, 5998–6008.

Look at what stays constant — same authors, title, venue, year — and what changes: where the year sits, whether authors are spelled out or collapsed to "et al.," brackets vs. parentheses vs. superscripts, commas vs. semicolons between names, what gets italicized, and whether the title uses sentence case (IEEE, APA) or title case (Chicago, ACS).

Example 2 — A book

The source (Tier 1): William Strunk Jr. and E. B. White, The Elements of Style, 4th edition, Allyn and Bacon, Boston, 2000.

IEEE
[2] W. Strunk Jr. and E. B. White, The Elements of Style, 4th ed.
    Boston, MA, USA: Allyn and Bacon, 2000.

APA  (in-text: (Strunk & White, 2000) )
Strunk, W., Jr., & White, E. B. (2000). The elements of style
    (4th ed.). Allyn and Bacon.

Chicago  (bibliography entry; note form drops the period inversions)
Strunk, William, Jr., and E. B. White. The Elements of Style. 4th ed.
    Boston: Allyn and Bacon, 2000.

ACS
(2) Strunk, W., Jr.; White, E. B. The Elements of Style, 4th ed.;
    Allyn and Bacon: Boston, 2000.

For a book, the field that moves most is the publisher and place: IEEE and ACS keep the city; modern APA (7th edition) drops the publisher location and lists the publisher alone. Note that APA and IEEE put the edition in parentheses or after a comma, while Chicago and ACS run it inline.

Example 3 — A web source

The source (Tier 1, real legislation/landmark page): "Plain Writing Act of 2010," PLAIN — Federal Plain Language Guidelines, U.S. General Services Administration, accessed June 3, 2026, https://www.plainlanguage.gov/law/. (Illustrative author/date for the page; verify the live page's own publication date before citing.)

IEEE
[3] U.S. General Services Administration, "Plain Writing Act of 2010,"
    PLAIN. Accessed: Jun. 3, 2026. [Online]. Available:
    https://www.plainlanguage.gov/law/

APA  (in-text: (U.S. General Services Administration, n.d.) )
U.S. General Services Administration. (n.d.). Plain Writing Act of
    2010. PLAIN. Retrieved June 3, 2026, from
    https://www.plainlanguage.gov/law/

Chicago  (note form)
3. U.S. General Services Administration, "Plain Writing Act of 2010,"
   PLAIN, accessed June 3, 2026, https://www.plainlanguage.gov/law/.

ACS
(3) Plain Writing Act of 2010. PLAIN. https://www.plainlanguage.gov/
    law/ (accessed 2026-06-03).

For web sources the critical extra field is the access date, because web pages change. When a page has no clear publication date, APA uses n.d. ("no date") and still records when you retrieved it. A DOI, when one exists, replaces the URL in APA and ACS and is more stable — prefer it.

What field uses which element — at a glance

Element IEEE APA Chicago (notes) ACS
In-text marker [1] (Author, Year) superscript → footnote superscript ¹
Author order First-initial Last Last, F. M. First Last (note) Last, F. M.
"et al." threshold ≥ 4 authors → et al. ≥ 21 → et al. (else list all) ≥ 4 → et al. (note) typically all, journal-dependent
Year position near the end right after authors near the end (note) after journal title
Title case sentence case sentence case title case title case
Page numbers pp. 5998–6008 issue/volume; pp. if needed as needed 30, 5998–6008

These thresholds and conventions shift between editions (APA 6th vs. 7th, IEEE updates). Treat this table as orientation, not gospel — the authoritative manual for your target always wins. See Appendix F for which manual that is.

Practical workflow (from Chapter 11)

  1. Pick the style your audience expects, and write the style name at the top of your draft so it's a conscious choice.
  2. Use a reference manager (Zotero, Mendeley) to store sources and generate the list. It can reformat an entire document from IEEE to APA in seconds when a target journal rejects you and the next one wants something else.
  3. Verify every generated entry. A manager formats wrong metadata flawlessly — a mistyped year or a missing author renders into a perfect-looking, incorrect citation. Accuracy is non-delegable.
  4. Never cite a source you can't confirm exists. AI tools and sloppy notes both produce realistic-looking references for papers that were never written. If you can't find it and confirm it says what you claim, don't cite it.

Citation-honesty note (this book's three tiers): The Vaswani, Strunk & White, and Plain Writing Act sources above are real (Tier 1). The specific page-access framing in Example 3 is illustrative — always confirm a live page's own date before citing it. Never invent a DOI, year, page range, or journal to make a citation look complete.