Madole, Richard F.; Bradley, William C.; Loewenherz, Deborah S.; Ritter, Dale F.; Rutter, Nathaniel W.; Thorn, Colin E. (1987). "Rocky Mountains". In Graf, William L. (ed.). Geomorphic Systems of North America. Decade of North American Geology. Vol. 2 (Centennial Special ed.). Geological Society of America (published January 1, 1987). pp. 211–257. doi:10.1130/DNAG-CENT-v2.211. ISBN9780813754147. Retrieved June 22, 2021.
Madole, Richard F.; Bradley, William C.; Loewenherz, Deborah S.; Ritter, Dale F.; Rutter, Nathaniel W.; Thorn, Colin E. (1987). "Rocky Mountains". In Graf, William L. (ed.). Geomorphic Systems of North America. Decade of North American Geology. Vol. 2 (Centennial Special ed.). Geological Society of America (published January 1, 1987). pp. 211–257. doi:10.1130/DNAG-CENT-v2.211. ISBN9780813754147. Retrieved June 22, 2021.