Author
United States. National Park Service
Geological Survey (U.S.)
4
Sonoran Desert Field Station (Tucson, Ariz.)
4
University of Arizona. School of Renewable Natural Resources
4
Halvorson, William L. 1943-
3
Powell, Brian F.
3
Schmidt, Cecilia A.
3
Colorado Natural Heritage Program
1
Drost, Charles A.
1
Gionfriddo, James Paul
1
Stevens, Joe
1
United States. Bureau of Land Management
1