My second source

, . (1997). Maximum Security : Anonymous: A Hacker's Guide to Protecting Your Internet Site and Network. Indianapolis, Ind.: Sams.net.

This book talks about the way that hackers usually use to attack to networks. This book is related to my research question because it explains how computer security can protect the network form these attacker. Also, it talks about the way that hackers hack the network, so it means computer security needs to update all the time. This book helps me to learn another idea that computer security can not protect system 100%.