Citation Style Guide

This reference defines the formatting rules for four major citation styles used in academic publishing. Use this when validating bibliography entries with verify_bib.py --style <style>.

Style Comparison Matrix

Feature	IEEE	APA 7th	Vancouver	Nature
In-text format	[1] numeric	(Smith, 2023) author-year	(1) or superscript	Superscript
Author threshold	6 → et al.	3 → et al. (in-text: 1-2 spell, 3+ et al.)	6 → et al.	5 → et al.
Journal name	ISO 4 abbreviated	Full name, italicized	NLM abbreviated	ISO 4 abbreviated
Volume	Bold	Italicized	Bold	Bold
Pages	en dash (pp. 1--10)	en dash (pp. 1--10)	en dash (1--10)	en dash (1--10)
DOI	Required when available	Required as URL	Optional	Required when available
Year position	After author	After author in parens	After journal	After journal

IEEE Style

In-text: [1], [2-4], [1], [3]

Reference format:

[1] A. B. Author, C. D. Author, and E. F. Author, "Article title," J. Abbrev., vol. 10, no. 2, pp. 1--15, Mar. 2023, doi: 10.xxxx/xxxxx.

Rules:

• Authors: initials before surname, up to 6 listed, then "et al."
• Title: sentence case in double quotes
• Journal: ISO 4 abbreviation, italicized
• Volume/number/pages: vol. X, no. Y, pp. A--B
• Month abbreviated: Jan., Feb., Mar., Apr., May, Jun., Jul., Aug., Sep., Oct., Nov., Dec.
• DOI required when available
• Pages use en dash (-- in BibTeX, renders as –)

APA 7th Edition

In-text: (Smith, 2023), (Smith & Jones, 2023), (Smith et al., 2023) for 3+

Reference format:

Author, A. B., Author, C. D., & Author, E. F. (2023). Article title. Journal Name, 10(2), 1--15. https://doi.org/10.xxxx/xxxxx

Rules:

• Authors: surname, initials; up to 20 listed, 21+ use first 19 + ... + last
• In-text: 1-2 authors spell out, 3+ use "et al."
• Title: sentence case, no quotes
• Journal: full name, italicized
• Volume italicized, issue in parentheses (not italicized)
• DOI formatted as URL: https://doi.org/10.xxxx/xxxxx
• Hanging indent (0.5 inch)
• No "pp." before page numbers in journals

Vancouver Style

In-text: (1) or superscript ¹, numbered by order of appearance

Reference format:

1. Author AB, Author CD, Author EF. Article title. J Abbrev. 2023;10(2):1-15.

Rules:

• Authors: surname followed by initials (no periods, no commas between initials)
• Up to 6 authors listed, then "et al."
• Title: sentence case, no quotes
• Journal: NLM (PubMed) abbreviation
• No spaces between volume, issue, pages: 2023;10(2):1-15
• DOI typically omitted in print; include for online-only
• Pages: en dash preferred but hyphen accepted

Nature Style

In-text: Superscript numbers ¹, ²,³, ⁴⁻⁶

Reference format:

1. Author, A. B., Author, C. D. & Author, E. F. Article title. J. Abbrev. 10, 1--15 (2023).

Rules:

• Authors: surname, initials; up to 5 listed, then "et al."
• Title: sentence case, no quotes, no period after title
• Journal: ISO 4 abbreviation, italicized
• Volume bold, pages with en dash, year in parentheses
• No "vol.", "no.", "pp." labels
• DOI required when available (appended after year)

En Dash Rule

All styles require en dash (–, Unicode U+2013) between page ranges, not hyphen (-).

In BibTeX: use -- which renders as en dash. Flag single hyphens in page fields.

Validation check: pages field should contain -- not a single -.

Unverifiable Fields

When a field cannot be confirmed (DOI not found, page numbers uncertain):

• English: mark as [Unverified]
• Chinese: mark as [待核实]
• Never fabricate DOI, page numbers, volume, or issue numbers
• Flag uncertain entries separately rather than guessing silently

Style Detection Heuristic

When --style is not specified, attempt detection from:

1. \bibliographystyle{IEEEtran} → IEEE
2. \bibliographystyle{apalike} or \usepackage{apacite} → APA
3. \bibliographystyle{vancouver} or \usepackage{vancouver} → Vancouver
4. Document class or preamble hints for Nature-family journals
5. Default: IEEE (most common in CS/EE)