LaTeX and BibTeX co-operate to offer special treatment of this
requirement. The command \nocite{*} is specially treated,
and causes BibTeX to generate bibliography entries for every entry
in each bib file listed in your \bibliography statement, so
that after a LaTeX–BibTeX–LaTeX sequence, you have a
document with the whole thing listed.
Note that LaTeX doesn’t produce
“Citation ... undefined” or
“There were undefined references” warnings in respect of
\nocite{*}. This isn’t a problem if you’re running
LaTeX “by hand” (you know exactly how many times you have
to run things), but the lack might confuse automatic processors that
scan the log file to determine whether another run is necessary.
A couple of packages are available, that aim to reduce the impact of
\nocite{*} of a large citation database. Biblist
was written for use under LaTeX 2.09, but seems to work well enough;
listbib is more modern. Both provide their own
bst files. (The impact of large databases was significant
in the old days of LaTeX systems with very little free memory; this
problem is less significant now than it once was.)
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=nocitestar