The "Canon Rangefinder Cameras 1933-68" book is proving to be most interesting, though I've had very little time so far to read it. Finding affordable copies of "Leica Copies by HPR" and "300 Leica Copies" is going to be "fun", but I think worth the effort. Given the current prices on "The Authentic Guide to Russian and Soviet Cameras", I think I'll have to get lucky to add that to my Library (in part because it's less of a priority, since the other two books should cover some of this).