1. "The Lost Dutchman Mine:" by Sims Ely 1953
This is the closest anybody is going to get to first hand information. Jim Bark knew Waltz. They both interviewed Julia Thomas and Rhinehardt Petrasch.
2. "Trail of the Lost Dutchman" by Barry Storm 1939
If you don't mind dropping some stiff money for a paperback, this is an excellent source for old photos and maps. A lot of good info here.
3. "Thunder God's Gold" Barry Storm 1945
Another expensive book to find, and is kind of an updated version of Trail of the Lost Dutchman". There are things in each book that aren't in the other (both are necessary).
4. "Arizona's Monument to Lost Mines" Jonathan Burbridge 1969
A great book. Lots of good pics.
Mike