BSD UNIX Toolbox: 1000+ Commands for FreeBSD, OpenBSD and NetBSD
The Best of Freebsd Basics
Building a Server with FreeBSD 7
Absolute FreeBSD: The Complete Guide to FreeBSD, 2nd Edition
DTrace: Dynamic Tracing in Oracle Solaris, Mac OS X and FreeBSD
Designing BSD Rootkits: An Introduction to Kernel Hacking
The Book of PF: A No-nonsense Guide to the Openbsd Firewall
The Definitive Guide to PC-BSD
The Design and Implementation of the FreeBSD Operating System
Network Administration with FreeBSD 7: Building, securing, and maintaining networks with the FreeBSD operating system