Mata-López, R., L. García-Prieto, and V. León-Règagnon. “Helminths of the American Bullfrog, Lithobates Catesbeianus (Shaw, 1802), from Pawnee Lake, Lancaster, Nebraska, USA With a Checklist of Its Helminth Parasites”. Zootaxa, vol. 2544, no. 1, July 2010, pp. 1–53, doi:10.11646/zootaxa.2544.1.1.