26.
Pilsbry H. A. 1893–1895. Manual of conchology, structural and systematic, with illustrations of the species. Ser. 2, Pulmonata. Vol. 9: Helicidae, Vol. 7, Guide to the study of Helices. pp. 1–225, pls 1–61. Philadelphia, published by the Conchological Section, Academy of Natural Sciences. [pp. 1–48, pls 1–14, 16 Nov 1893; pp. 49–112, pls 15–28, 19 Mar 1894; pp. 113–160, pls 29–40, 27 Jul 1894; pp. 161–366, pls 41–71, i–xlviii, 2 Feb 1895; index 1–126, April 1895].