Sowerby, G. B. II. (1875-1878). Monograph of the genus
Pupa. In:
Conchologia iconica, or illustrations of the shells of molluscous animals, vol. 20, pl. 1-20 and unpaginated text. L. Reeve, London. [pls. 2, 1875, no month date; 3-19, 1876, no month date; 1, 20, 1878, no month date].