Benson, Lyman; and Darrow, Robert: _A Manual of Southwestern Trees and
Shrubs_; University of Arizona, 1944.
Benson, Lyman: _The Cacti of Arizona_; University of Arizona, Second
Edition, 1950.
Black, Homer: _Common and Larger Plants Near the Cavern Entrance_;
Carlsbad Caverns National Park; mss. 1944.
Cooper, Norman C.: _Check List of Plants of Organ Pipe Cactus National
Monument_; mss. 1942.
Jaeger, Edmund C.: _Desert Wildflowers_; Stanford University Press,
Revised Edition, 1944.
Joint Committee on Horticultural Nomenclature: _Standardized Plant
Names_; Second Edition, 1942.
Kearney, Thomas H.; and Peebles, Robert H.: _Flowering Plants and Ferns
of Arizona_; Government Printing Office, 1942.
McDougall, W. B.: Vegetation of White Sands National Monument; mss.
1939.
McDougall, W. B.: Check List of the Plants of Death Valley National
Monument; mimeo. 1945.
McDougall, W. B.; and Sperry, Omer E.: Plants of Big Bend National Park;
Government Printing Office, 1951.
Nichol, A. A.: _The Natural Vegetation of Arizona_; University of
Arizona Technical Bulletin No. 68, 1937.
Shantz, H. L.; and Piemeisel, R. L.: _Indicator Significance of the
Natural Vegetation of the Southwestern Desert Region_; Government
Printing Office, 1925.
Sperry, Omer E.; and Warnock, Barton H.: _Plants of Brewster County,
Texas_; Sul Ross State Teachers College Bulletin, Vol. 21, No. 1,
Alpine, Texas, 1941.
Taylor, Walter P.; McDougall, Walter B.; and Davis, William B.:
_Preliminary Report of an Ecological Survey of Big Bend National
Park_; March-June, 1944; mimeo.