Here's a site for FREE PDF books on a variety of armor. You can download 1 book per 30 mins., or sign up for unlimited downloads, at a cost of course. This link is just to one page of many to give you an idea of what's there, at the bottom of the page you can search or click newer/older posts to navigate.
[link]http://military-machine.blogspot.com/search/label/Armour?updated-max=2010-02-18T07%3A01%3A00-08%3A00&max-results=20[/link]

Enjoy,
Dean