Special Symbols in BibTeX
BibTeX fields may contain LaTeX. This page shows how to write accented and special characters, which characters need escaping, and how to stop styles from changing your capitalization.
On this page
Protecting capital letters
Many styles change titles to sentence case, so An Introduction to BibTeX becomes An introduction to bibtex. Text inside an extra pair of braces is left exactly as written:
title = {An Introduction to {BibTeX}}
title = {Bayesian Methods for {DNA} Sequencing in {Europe}}Brace single words or acronyms rather than the whole title. That way the style can still apply its own capitalization to everything else. Wrapping the whole title in double braces ({{...}}) works, but it hides the title from the style entirely.
Accents and umlauts
Accents are written with the usual LaTeX commands. Put the whole command in braces, like {\"o}. BibTeX then treats it as a single special character: it sorts it correctly, won’t change its case, and keeps it intact when abbreviating first names.
author = {G{\"o}del, Kurt and Erd{\H{o}}s, Paul}
title = {Na{\"\i}ve Set Theory, {\'E}tudes, and {\AA}ngstr{\"o}m Units}| Command | Result | Command | Result |
|---|---|---|---|
{\'e} |
é | {\c{c}} |
ç |
{\`e} |
è | {\k{a}} |
ą |
{\^e} |
ê | {\v{s}} |
š |
{\"o} |
ö | {\u{g}} |
ğ |
{\H{o}} |
ő | {\r{a}} |
å |
{\~n} |
ñ | {\={a}} |
ā |
{\.z} |
ż | {\d{a}} |
ạ |
{\"\i} |
ï (dotless i with umlaut) | {\ss} |
ß |
{\o}, {\O} |
ø, Ø | {\l}, {\L} |
ł, Ł |
{\aa}, {\AA} |
å, Å | {\ae}, {\AE} |
æ, Æ |
{\oe}, {\OE} |
œ, Œ | {\i}, {\j} |
ı, ȷ |
Unicode
With biblatex and biber, you can simply type the characters in UTF-8: author = {Gödel, Kurt}. The same works with classic BibTeX in most modern setups, since LaTeX reads UTF-8 by default. However, BibTeX itself doesn’t understand multi-byte characters. It may sort them wrongly, and styles that abbreviate first names can cut them in half. If you depend on classic BibTeX, the LaTeX commands above are the safest choice.
Characters that need escaping
Some characters have a special meaning in LaTeX or BibTeX and must be escaped with a backslash when you mean the character itself:
| Character | Write | Note |
|---|---|---|
| & | \& |
Very common in journal and publisher names |
| % | \% |
Otherwise starts a LaTeX comment |
| $ | \$ |
Otherwise starts math mode |
| # | \# |
Otherwise BibTeX’s concatenation operator |
| _ | \_ |
Except inside \url{...} |
| { } | \{ \} |
Braces must be balanced in any case |
| “ | {"} |
Only inside quote-delimited values |
| ~ | \textasciitilde{} |
A plain ~ is a non-breaking space |
URLs are the exception: in url fields, and inside \url{...}, write them exactly as they are. The url and hyperref packages take care of special characters.
LaTeX commands and math
Fields may contain LaTeX commands, which are processed when the bibliography is typeset. For example, \emph, \textsc or \TeX:
title = {The {\TeX}book}
title = {Clustering in {\emph{Drosophila}} Genomes}
title = {The $20^{th}$ Annual Meeting of {BibTeX} Users}
title = {Improved Bounds for the ${O}(n \log n)$ Case}Wrap commands in braces as shown, so a sentence-case style doesn’t change their capitalization. Math mode works as usual; put upper-case letters in formulas in braces too.