Baker, F.C. 1939. Fieldbook of Illinois Land Snails. Natural History Survey Division, State of Illinois. Urbana, Illinois. (used for comparison of Western and Eastern Whitelips)
Burch, J.B. 1962. How to Know the Eastern Land Snails. Wm. C. Brown Company Publishers, Dubuque, Iowa. 214 pp. An online pdf is available to see.
Dourson, D.C. 2010. Kentucky’s Land Snails and their Ecological Communities. Goatslug Publications, Bakersville, NC. 298 pp.
Dourson, D.C. 2015. Land snails of West Virginia. Goatslug Publications, Bakersville, NC. 412 pp.
Hotopp, K.P., T.A. Pearce, J.C. Nekola, J. Slapcinsky, D.C. Dourson, M. Winslow, G. Kimber, and B. Watson. 2013. Land Snails and Slugs of the Mid-Atlantic and Northeastern United States. Carnegie Museum of Natural History, Pittsburgh, PA. Online Resource: http://www.carnegiemnh.org/science/mollusks/index.html. (Note: a very good source for descriptions and images of many snails found in Indiana. Their Pennsylvania and Virginia datasets work pretty well.)
Hubricht, L. 1958. New species of land snails from the eastern United States. Transactions of the Kentucky Academy of Science, 19(3-4): 70-76. (used for Stenotrema angellum)
Hubricht, L. 1985. The distributions of the native land mollusks of the eastern United States. Fieldiana: Zoology, New Series, No. 24: 1-191.
NatureServe. 2020-2021. NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org/. (Accessed at various times. A good source for distributions and conservation status.).
Nekola, J.C. and B.F. Coles. 2010. Pupillid land snails of eastern North America. Bulletin of the American Malacological Society. 28:1-29. (Excellent source for Gastrocopa, Pupillids, and Vertigo.)
Oesch, R.D., L.E. Watrous, and M. C. Barnhart. 2013. Land Snails and Slugs of Missouri. Missouri Department of Conservation, Jefferson City, Missouri. (The link opens a pdf of the publication. This is a good supplementary source of descriptions and images.)
Thomas, A.K., R.J. Mc Donnell, T.D. Paine, and J.D. Harwood. 2010. A Field Guide to the Slugs of Kentucky. SR-103. Agricultural Experiment Station, College of Agriculture, Lexington, KY. pp 36. (The link opens a pdf of the publication. This covers invasive species including the slug Deroceras laeve, which is considered both native and exotic to North America, but leaves out the native Philomycids.)