I own two of these - they are AMAZING references for anyone wheeling in the US.
Gunther, I'd like to buy the Arizona book and the Colorado book that I don't already own. I think that's the Northern Colorado book, since the one I already have covers the San Juans and Sangre de Cristo range. The challenge is that I'm in Ottawa at the moment, and currently living in Edmonton. Any chance you can hang onto them for me for a little bit until I can pick them up?
For anyone planning a trip to Moab, Ouray, Silverton, or places like that, these books are 100% the best tool you can have for figuring out where to wheel - and come a close second to wheeling experience for avoiding situations where you end up in real trouble. They offer a trail-by-trail outline of how to get to the trail, where the gnarly obstacles are, and some good route planning as well.