Frost, Darrel «The Amphibian Tree of Life». Bulletin of the American Museum of Natural History, vol. 297, 2006, pàg. 1–371.
Pauly, G. B., D. M. Hillis, i D. C. Cannatella. (2004) The history of a Nearctic colonization: Molecular phylogenetics and biogeography of the Nearctic toads (Bufo). Evolution58: 2517–2535.