Harding, James; Mifsud, David (2017). Amphibians and Reptiles of the Great Lakes Region. Ann Arbor, MI: University of Michigan Press. doi:10.3998/mpub.8158052. ISBN978-0-472-07338-2.
Savitzky, Alan H. (2004), Hutchins, Michael; Evans, Arthur V.; Jackson, Jerome A.; Kleiman, Devra G. (eds.), Grzimek's Animal Life Encyclopedia, vol. 7: Reptiles (2nd ed.), Detroit: Adam, p. 47, archived from the original on 2011-05-21, retrieved 2018-12-03
Savitzky, Alan H. (2004), Hutchins, Michael; Evans, Arthur V.; Jackson, Jerome A.; Kleiman, Devra G. (eds.), Grzimek's Animal Life Encyclopedia, vol. 7: Reptiles (2nd ed.), Detroit: Adam, p. 47, archived from the original on 2011-05-21, retrieved 2018-12-03
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Tennant, Alan. (2003). Snakes of North America: eastern and central regions. Lone Star Books. ISBN1-58907-003-8. OCLC632838334.