1. Alden, K. J. 1995. Helminths of the opossum, Didelphis virginiana., in southern Illinois, with a compilation of all helminths reported from this host in North America. Journal of the Helminthological Society of Washington 62: 197–208.
2. Andrews, K. D., Lampley, R. L., Gillman, M. A., Corey, D. T., Ballard, S. R., Blasczyk, M. J., and Dyer, W. G. 1992. Helminths of Rana catesbeiana. in southern Illinois with a checklist of helminths in bullfrogs of North America. Transactions of the Illinois State Academy of Science 85: 147–172.
3. Beasley, V. R., Faeh, S. A., Wikoff, B., Staehle, C., Eisold, J., Nichols, D., Cole, R., Schotthoefer, A. M., Greenwell, M., and Brown, L. E. 2005. Risk factors and the decline of the cricket frog, Acris crepitans: evidence for involvement of herbicides, parasitism, and habitat modificationsLannoo, M. J., Amphibian Declines: The Conservation Status of United States Species, University of Chicago Press.Chicago: 75–87
4. Beaver, P. C. 1937. Experimental studies on Echinostoma revolutum. (Froelich) a fluke from birds and mammals. Illinois Biological Monographs 15: 1–96.
5. Beaver, P. C. 1939. The morphology and life history of Psilostomum ondatrae, Price 1931 (Trematoda: Psilostomidae), Journal of Parasitology 25: 383–393.