The second edition of the book “Security Engineering” by Ross Anderson is available as a full download. It’s quite a reference and a must-read for anybody with an interest in security (which for example all developers should have).
“When I wrote the first edition, we put the chapters online free after four years and found that this boosted sales of the paper edition. People would find a useful chapter online and then buy the book to have it as a reference. Wiley and I agreed to do the same with the second edition, and now, four years after publication, I am putting all the chapters online for free. Enjoy them – and I hope you’ll buy the paper version to have as a conveient shelf reference.”
Source 1: http://www.cl.cam.ac.uk/~rja14/book.html