@inbook{NARMS:SourceID:380574, author = {Sowerby, G. B. II}, title = {Monograph of the genus Pteropoda. In: Conchologia iconica, or illustrations of the shells of molluscous animals, vol. 20: pls 1-6 and unpaginated text. L. A. Reeve, London. [1877, no month date]}, url = {https://www.biodiversitylibrary.org/page/8230531}, year = {1877} }