1. Barnes, R. D. 1968. Invertebrate Zoology, 2nd Edition. W. B. Saunders Company, Philadelphia, PA, USA.
2. Borror, D. J., D. M. De Long, and C. A. Triplehorn 1981. An Introduction to the Study of Insects, 5th Edition. Saunders College Publishing, New York, NY, USA.
3. Clarke, A. H. 1981. The Freshwater Molluscs of Canada. National Museum of Natural Sciences, Ottawa, ON, Canada.
4. FWS/OBS-79/31;L. M. Cowardin,1979
5. Cowardin, L. M., D. H. Johnson, T. L. Shaffer, and D. W. Sparling. 1988. Applications of a simulation model to decisions in mallard management. U.S. Fish and Wildlife Service Technical Report 17.