Document: BTXDOC ["BibTeXing" by Oren Patashnik]
3.1 Entry Types
BibTeXing
2.2 Changes to the standard styles
This section is simply a corrected version of
Appendix B.2 of the 
book (Lamport 1986),
© 1986, by Addison-Wesley.
The basic scheme is the same, only a few details have changed.