Hacking VoIP: Protocols, Attacks, and Countermeasures
Himanshu Dwivedi
Defensive Security Handbook: Best Practices for Securing Infrastructure
Lee Brotherston & Amanda Berlin
Database System Concepts 6th Edition
Abraham Silberschatz & Henry Korth & S. Sudarshan
The UNIX Programming Environment
Brian Wilson Kernighan & Rob. Pike
Gchq
Richard Aldrich