^Boulenger, G.A. 1896. Catalogue of the Snakes in the British Museum (Natural History). Volume III., Containing the Colubridæ (Opisthoglyphæ and Proteroglyphæ),... Trustees of the British Museum (Natural History). (Taylor and Francis, Printers.) London. xiv + 727 pp. + Plates I.- XXV. (Zamenis grahamiæ Var. hexalepis, p. 622.)
^Stejneger, L., and T. Barbour. 1917. A Checklist of North American Amphibians and Reptiles. Harvard University Press. Cambridge, Massachusetts. 125 pp. (Salvadora hexalepis, p. 81.)