1. Duellman, W. E. Univ. Kan. Mus. Nat. Hist. Spec. Pub. 21, 1–372 (1993).
2. Estes, R. & Reig, O. A. in Evolutionary Biology of the Anurans (ed. Vial, J. L.) 11–63 (University of Missouri Press, Columbia, 1973).
3. Trueb, L. in Evolutionary Biology of the Anurans (ed. Vial, J. L.) 65–132 (University of Missouri Press, Columbia, 1973).
4. Duellman, W. E. & Trueb, L. Biology of Amphibians (McGraw-Hill, New York, 1986).
5. Milner, A. R. in The Phylogeny and Classification of the Tetrapods. 1. Amphibians, Reptiles. Birds (ed. Benton, M. J.) 59–102 (Clarendon, Oxford, 1988).