Hyman, Libbie Henrietta. The Invertebrates: Aplacophora, Polyplacophora, Monoplacophora, Gastropoda The Coelomate Bilateria / - 1st ed / - New York : McGraw-Hill Book Company , 1962 - p.792 : ISBN: 07-031668-4 Dewey Class. No.: K1 / J1;1