BibTeX, a program originally designed to produce bibliographies in
conjunction with LaTeX, is explained in Section 4.3 and Appendix B
of Leslie Lamport's LaTeX manual.
The document “BibTeXing”, in the BibTeX distribution (look for
expands on the chapter in Lamport's book. The LaTeX Companion
also has information on BibTeX and writing BibTeX style files.
(See LaTeX books for details of both
The web site “Your BibTeX resource” offers a solid introduction, but doesn't go into very great detail.
The document “Designing BibTeX Styles”, also in the BibTeX
distribution (look for
btxhak), explains the postfix stack-based language used to
write BibTeX styles (
.bst files). The file
also in the BibTeX distribution,
is the template for the four standard styles (plain,
abbrv, alpha, and unsrt); it also
contains their documentation.
A useful tutorial of the whole process of using BibTeX is Nicolas Markey's “Tame the BeaST (The B to X of BibTeX)”, which may also be found on CTAN. A summary and FAQ by Michael Shell and David Hoadley, is also to be recommended.