Sowerby, G. B. II. (1865-1866). Monograph of the genus
Vertagus.
In: Conchologia Iconica, or, illustrations of the shells of molluscous animals. vol. 15, pls 1-5 and unpaginated text. L. Reeve & Co., London [stated dates: pl. 1, 3, 5, March 1866; pl. 2, December 1865; pl. 4, March 1865].