Duellman, William E.; Zug, George R. "Anura: Critical appraisal". Encyclopædia Britannica. Retrieved 24 September 2012.
cortland.edu
Ducey, Peter, Dr. (n.d.). Cramer, Craig (ed.). "Glossary". Biology SUNY Cortland. Cortland Herpetology Connection. Cortland, NY: State University of New York.{{cite web}}: CS1 maint: multiple names: authors list (link)
Vitt, Laurie J. & Caldwell, Janalee P. (2014). Herpetology: An Introductory Biology of Amphibians and Reptiles (4th ed.). Academic Press. ISBN9780123869197. OCLC839312807.