Badra, P.J. 2008. Special Animal Abstract for Planogyra asteriscus (eastern flat- whorl). Michigan Natural Features Inventory. Lansing, MI. 4pp.

Baker, F. C. "Land and freshwater mollusca from North Star Lake and vicinity, Itasca County, Minnesota." The American midland naturalist 16.3 (1935):257.

Encyclopedia of Life. Available from Accessed 15 Jan 2009

Martin, S M. (2000). Terrestrial snails and slugs (mollusca: Gastropoda) of maine. Northeastern naturalist, 7    (1), 33.

Nordsieck, R. (1999-2010): "The living world of molluscs",

Tryon, G.W. (1866). American Journal of Conchology,2, 263 & 276.

Winslow, M.L. (1926). Occasional papers of the museum of zoology a revised checklist of michigan mollusca. University of Michigan Press, (181), 1-28