I found this book interesting. This is a short book, only 68 pages of concise material about security. The book explains how to make a plan to build a more secure Web Application and how to use the appropriate tools to track the weakness of the Web Site Applications of a company.
Everything is on the Internet now. But some companies are not aware of the risks they are exposed to. It's not only the shutdown of the Web site that is very serious, but more serious is the loss of client data or the enterprise's data.
Hackers are constantly searching for opportunities to enter your system and steal the data from the site. The company has to be aware of it and take the appropriate measures to prevent these attacks.
An interest point is that the book mentions some tools for diagnosis which allow looking for errors in the code of the application and not only the network that transports the data as people usually do.
In any case, you can download the book for free in this link: