Pilsbry, H. A. (1897-1898).
Manual of conchology, structural and systematic, with illustrations of the species. Ser. 2, Pulmonata. Vol. 11: American Bulimulidae:
Bulimulus, Neopetraeus, Oxychona, and South American
Drymaeus. pp 1-339, pls 1-51. Philadelphia, published by the Conchological Section, Academy of Natural Sciences. [pp. 1-64, pls. 1-13, May 11, 1897; pp. 65-144, pls. 14-25, Oct. 15, 1897; pp. 145-208, pls. 27-41, May 3, 1898; pp. 209-339, pls. 26, 42-51, Dec. 7, 1898].