CompTIA Linux+ Guide to Linux Certification
Jason Eckert
Metasploit Penetration Testing Cookbook
Abhinav Singh
Linux® Command Line and Shell Scripting Bible
Richard Blum
The Linux Command Line
William E. Shotts, Jr.
Introduction to Sociology 2e
Heather Griffiths & Nathan Keirns & Gail Scaramuzzo & Susan Cody-Rydzewski & Eric Strayer & Sally Vyrain