Pilsbry, H. A. (1920-1921). Manual of conchology, structural and systematic, with illustrations of the species. Ser. 2, Pulmonata. Vol. 26: Pupillidae (Vertigininae, Pupillinae). pp i-iv, 1-254, pls 1-24. Philadelphia, published by the Conchological Section, Academy of Natural Sciences. [pp. 1-64, pls 1-8, 23 Dec 1920; pp. 65-128, pls 9-13, 13 May 1921; pp. 129-192, pls 14-18, , figs. 1-4, 4 Aug 1921; pp. 193-254, pls 19-24, figs. 1-4, 21 Dec 1921].
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Pilsbry, H. A.
1920-1921
<i>Manual of conchology, structural and systematic, with illustrations of the species</i>. Ser. 2, Pulmonata. Vol. 26: Pupillidae (Vertigininae, Pupillinae). pp i-iv, 1-254, pls 1-24. Philadelphia, published by the Conchological Section, Academy of Natural Sciences. [pp. 1-64, pls 1-8, 23 Dec 1920; pp. 65-128, pls 9-13, 13 May 1921; pp. 129-192, pls 14-18, , figs. 1-4, 4 Aug 1921; pp. 193-254, pls 19-24, figs. 1-4, 21 Dec 1921]