A C&R gun with lots of fans must be a gun with rich history. I feel John Walter's "The Luger Story" is an excellent starting point. It does not look into details of guns and accessories like other books, but it covers the origin, history, and transition of Lugers, in plain English.
The older edition is available on Amazon, a little more than $20. Start from top to see the whole picture, then acquiring other references going down into details.... that works for me so far. Of course, nothing replaces holding guns in hands to study them.
http://www.amazon.com/Luger-Story-St.../dp/0905778774