# Entry format

A bibliography database file contains a series of reference entries like the following:

```      @BOOK{kn:gnus,
AUTHOR = "Donald E. Knudson",
TITLE  = "1966 World Gnus Almanac",
PUBLISHER = {Permafrost Press},
```

The @BOOK states that this is an entry of type book. various entry types are described below. The 'kn:gnus' is the citation key, as it appears in the argument of a \cite command referring to the entry.

This entry has four fields, named AUTHOR, TITLE, PUBLISHER and ADDRESS. The meanings of these and other fields are described below. A field consists of the name, an '=' character with optional space around it, followed by its text. The text of a field is a string of characters, with no unmatched braces, surrounded by either a pair of braces or a pair of '"' characters. Entry fields are separated from one another, and from the citation key, by commas. A comma may have optional space around it.

The outermost braces that surround the entire entry may be replaced by parentheses. As in TeX input files, an end-of-line character counts as a space and one space is equivalent to many spaces. Unlike TeX, BibTeX ignores the case of letters in the entry type, citation key and field names. The above entry could have been typed as follows:

```        @BOOK(kn:gnus,  author = {Donald E. Knudson},
TITLE  = "1966 World Gnus
Almanac",
PUBLISHER = {Permafrost Press},
```                Volume = "27"           Volume = 27