| Eckel, Edwin Butt , Cobban, Robert R., Mosburg, Shirley K., Foord, Eugene E. (1997) Minerals of Colorado. Fulcrum Publishing. Armbrustmacher, T. J. (1988) Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer counties, Colorado. USGS Professional Paper: 1049-F USGS Prof Paper 649 |