BibTeX Bibliography Styles

What a style does

A BibTeX style is a .bst file. It defines which fields are printed for each entry type, how names are written, how the list is sorted and what the citation label looks like. Your .bib file stays the same; switching styles is a one-line change:

\bibliographystyle{plain}    % plain.bst, without the extension
\bibliography{references}

Run bibtex again after changing the style, then LaTeX twice (see How to Use BibTeX).

The four standard styles

plain, unsrt, alpha and abbrv are part of BibTeX itself. The examples below use these three entries, cited in the order Shannon, Knuth, Einstein:

@article{shannon1948,
  author  = {Shannon, Claude E.},
  title   = {A Mathematical Theory of Communication},
  journal = {Bell System Technical Journal},
  year    = {1948},
  volume  = {27},
  number  = {3},
  pages   = {379--423},
  month   = jul
}

@book{knuth1984,
  author    = {Knuth, Donald E.},
  title     = {The {\TeX}book},
  publisher = {Addison-Wesley},
  address   = {Reading, Massachusetts},
  year      = {1984}
}

@article{einstein1935,
  author  = {Einstein, Albert and Podolsky, Boris and Rosen, Nathan},
  title   = {Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?},
  journal = {Physical Review},
  year    = {1935},
  volume  = {47},
  number  = {10},
  pages   = {777--780}
}

plain

Numeric labels, full first names, sorted alphabetically by author, then year, then title. In the text the three citations appear as [3], [2] and [1].

[1] Albert Einstein, Boris Podolsky, and Nathan Rosen. Can quantum-mechanical description of physical reality be considered complete? Physical Review, 47(10):777–780, 1935.

[2] Donald E. Knuth. The TeXbook. Addison-Wesley, Reading, Massachusetts, 1984.

[3] Claude E. Shannon. A mathematical theory of communication. Bell System Technical Journal, 27(3):379–423, July 1948.

unsrt

Formatted exactly like plain, but listed in the order of first citation. In the text: [1], [2], [3].

[1] Claude E. Shannon. A mathematical theory of communication. Bell System Technical Journal, 27(3):379–423, July 1948.

[2] Donald E. Knuth. The TeXbook. Addison-Wesley, Reading, Massachusetts, 1984.

[3] Albert Einstein, Boris Podolsky, and Nathan Rosen. Can quantum-mechanical description of physical reality be considered complete? Physical Review, 47(10):777–780, 1935.

alpha

Formatted like plain, with labels built from the authors and the last two digits of the year, and sorted by label. One author gives the first three letters of the last name, two to four authors give their initials, and more than four give three initials followed by a superscript plus sign. In the text: [Sha48], [Knu84], [EPR35].

[EPR35] Albert Einstein, Boris Podolsky, and Nathan Rosen. Can quantum-mechanical description of physical reality be considered complete? Physical Review, 47(10):777–780, 1935.

[Knu84] Donald E. Knuth. The TeXbook. Addison-Wesley, Reading, Massachusetts, 1984.

[Sha48] Claude E. Shannon. A mathematical theory of communication. Bell System Technical Journal, 27(3):379–423, July 1948.

abbrv

Sorted and numbered like plain, with first names reduced to initials. Month names and the predefined journal abbreviations are shortened as well, so month = jul still prints as “July”, but month = sep gives “Sept.” and journal = jacm gives “J. ACM” instead of “Journal of the ACM”.

[1] A. Einstein, B. Podolsky, and N. Rosen. Can quantum-mechanical description of physical reality be considered complete? Physical Review, 47(10):777–780, 1935.

[2] D. E. Knuth. The TeXbook. Addison-Wesley, Reading, Massachusetts, 1984.

[3] C. E. Shannon. A mathematical theory of communication. Bell System Technical Journal, 27(3):379–423, July 1948.

All four styles lowercase article titles after the first word and ignore doi and url fields. See common problems.

Author-year styles with natbib

The standard styles only support numeric or alphabetic labels. For citations such as Einstein et al. (1935), load natbib and use plainnat, abbrvnat or unsrtnat. They format entries like their standard counterparts and additionally print doi, url, isbn and issn.

\usepackage[round]{natbib}
\bibliographystyle{plainnat}

The reference list has no labels and is sorted by author (unsrtnat: by citation order). With \usepackage[numbers]{natbib} the same styles produce numeric citations.

Which style for which requirement

If you write for a journal or conference, use the .bst file from its template. Otherwise:

ieeetr, acm and siam in the base distribution are older approximations of these publishers’ layouts. Prefer IEEEtran and ACM-Reference-Format for actual submissions. “Harvard” is not one defined format but a family of author-year styles, so plainnat with natbib is usually acceptable too. Science has no style on CTAN; use the files from the journal’s author instructions.

Finding and installing a style

A full TeX Live installation contains about 400 .bst files; small installations such as BasicTeX have far fewer. To check whether a style is installed, ask for its location:

kpsewhich IEEEtran.bst

If nothing is printed, install the package that contains it (tlmgr install ieeetran, or the MiKTeX Console), or download the file from CTAN or the publisher’s template. A .bst file placed in the same directory as your .tex file is found without any installation, which is the simplest way to use a journal’s style.

Making your own style

The custom-bib package generates a style from a questionnaire, so you don’t have to write the .bst language by hand:

latex makebst

It asks a long series of questions (label type, name format, punctuation, “et al.” thresholds, …) and writes a .dbj file. Running latex on that file produces the .bst. Keep the .dbj: you can edit single answers in it and regenerate the style.

When to switch to biblatex

Stay with a .bst style when a publisher requires one. Consider biblatex when you need APA 7, footnote or “ibid.” citations, sorting of non-English names, per-chapter bibliographies, or small adjustments that would otherwise mean generating a new .bst.

Common problems

• The doi or url field is not printed. The standard styles predate both. Use plainnat, abbrvnat or unsrtnat, or the urlbst variants plainurl, unsrturl, alphaurl and abbrvurl, which need no other changes.
• Capital letters in titles disappear. Most styles convert titles of articles to sentence case. Protect names and acronyms with braces: {Bell} inequalities. Details under protecting capital letters.
• “et al.” appears, or doesn’t. The standard styles always list every author in the bibliography; “et al.” is printed only where the .bib file says and others. natbib citations abbreviate from three authors on. Styles such as IEEEtran have a configurable threshold, and makebst lets you choose one.
• Citations show as [?] or the old format remains. Run bibtex again and then LaTeX twice. If it persists, delete the .bbl and .aux files, since a .bbl written by one style can be incompatible with the next.
• \citet is undefined, or author-year citations print as numbers. Author-year styles need their package (natbib, apacite, harvard) loaded in the preamble.