Author
Geological Survey (U.S.)
5
Schmidt, Cecilia A.
Halvorson, William L. 1943-
4
Powell, Brian F.
3
Sonoran Desert Field Station (Tucson, Ariz.)
3
United States. National Park Service
3
University of Arizona. School of Renewable Natural Resources
3
University of Arizona. School of Natural Resources
2
Drost, Charles A.
1