Colorado Cacti—Chas. H. Boissevain and Carol Davidson Abbey Garden Press, San Marino, 1940
Rocky Mountain Flowers—Frederic E. and Edith S. Clements H. W. Wilson Co., N. Y., 1920
New Manual of Botany of the Central Rocky Mountains—John Coulter and Aven Nelson American Book Co., Chicago, 1909
Manual of the Plants of Colorado—H. D. Harrington Sage Press, Ft. Collins, Colorado—in press, 1953
American Wild Flowers—Harold N. Moldenke D. Van Nostrand Company, Inc., N. Y., 1949
Meet the Natives—M. Walter Pesman Denver, Colorado, 1943
Flora of Colorado—P. A. Rydberg Ft. Collins, Colorado, 1906
Flora of Rocky Mountains and Adjacent Plains—P. A. Rydberg New York, 1917
The Flora of Boulder County, Colorado—William A. Weber University of Colorado Museum