One good source of additional information is the ``[comp.unix.bsd] NetBSD, FreeBSD, and 386BSD (0.1) FAQ''. Much of the information is relevant to FreeBSD, and this FAQ is posted around twice a month to the following newsgroups:
comp.unix.bsd.netbsd.announce comp.unix.bsd.freebsd.announce comp.answers news.answers
If you have WWW access, the FreeBSD home page is at:
The FreeBSD handbook has a pretty complete bibliography, look at: Bibliography