Cisco ASA Firewall Fundamentals
by Harris Andrea
This ones a great read for anyone first getting into ASA firewalls. Its a short book (about 150 pages) but goes through all the most common tasks one would do administering a firewall. Once you get your feet wet with this one, go to the Cisco Press Cisco ASA 3rd edition book (alot more detailed than this one). Great for a quick review for veterans.