Timberlake, J.R.; Childes, S.L. (2004). "Biodiversity of the Four Corners Area: Technical Reviews"(PDF). Occasional Publications in Biodiversity. 2 (15): 22.
(Chapters 5-15).
Occasional Publications in Biodiversity No 15,
Biodiversity Foundation for Africa, Bulawayo/Zambezi Society, Harare, Zimbabwe.