Cowie, Robert H.; Dillon, Robert T.; Robinson, David G.; Smith, James W. (2009). "Alien non-marine snails and slugs of priority quarantine importance in the United States: A preliminary risk assessment". American Malacological Bulletin. 27 (1–2): 113–132. doi:10.4003/006.027.0210. Archived 2016-06-16 at the Wayback Machine
Cowie, Robert H.; Dillon, Robert T.; Robinson, David G.; Smith, James W. (2009). "Alien non-marine snails and slugs of priority quarantine importance in the United States: A preliminary risk assessment". American Malacological Bulletin. 27 (1–2): 113–132. doi:10.4003/006.027.0210. Archived 2016-06-16 at the Wayback Machine