Pilsbry, H. A. (1922-1926).
Manual of conchology, structural and systematic, with illustrations of the species. Ser. 2, Pulmonata. Vol. 27: Pupillidae (Orculinae, Pagodulinae, Acanthinulinae, etc.). pp i-iv, 1-369, pls 1-32. Philadelphia, published by the Conchological Department, Academy of Natural Sciences. [pp. 1-80 Pl. 1-5, 29 Aug 1922; pp. 81-128 Pl. 6-11, 13 Jun 1923; pp. 129-176 Pl. 12-18, 16 Jul 1924; pp. 177-369, i-iv, figs. 1-17, Pl. 19-32, 01 April, 1926].