Palmer, Ernest J. 1920. The Canyon Flora of the Edwards Plateau of Texas. Bray, W.L. 1901. Ecological relations of the vegetation of western Texas. Bentley, H.L. 1898.
Cattle ranges of the Southwest.
Mecke, Mike. 1978. Texotics-exotic ungulates in Texas. Unpublished Graduate Paper, University of Wyoming. 12. Taylor, Charles, Editor. Mecke, Mike. 1963.