Grewal P.S, Grewal S. K, Tan L.  and Adams B.J, 2003. Parasitism of Molluscs by Nematodes: Types of Associations and Evolutionary Trends. Journal of Nematology 35(2) 146-156

Proschwitz T. V, Schander C, Jueng U, and Thorkildsen S, 2009 Morphology, Ecology and DNA-Barcoding Distinguish Pupilla pratensis (Clessin, 1871) from Pupilla muscorum (Linnæus 1758) (Pumonata:Pupillidae)

Animal Base 2010, <>. Accessed 25 March 2011

Hubricht, L. 1985. The Distribution of the Native Land Molluscs of the Eastern United States

Hickman C. P, Roberts L. S, Keen S.L, Larson A, and Eisenhour D. J, 2007. Animal Diversity Fifth Edition. McGraw-Hill Companies Inc, New York, New York, USA.

Discover Life, Pupilla muscorum (Linneaus, 1758) <>. Accessed 26 March 2011

Dedov I. K, 1998. An Annotated Check-list of the Bulgarian Terrestrial Snails.

Franzen D, 1947. Living and Fossil Pupillidae (Gastropoda) of the Sanborn Area, Northwestern Kansas

Burch J, 1962. How to Know the Eastern Land Snails. WM.C Brown Company, Dubuque, Iowa, USA.

The Living World of Molluscs 2010, <> Accessed 28 March 2011