M. M.  Schepman, ?The Mollusca of the Dutch Scientific Borneo-Expedition?, Notes from the Leyden Museum, vol. 17, pp. 145-162, 1896.

E. A.  Smith, ?On a collection of land-shells from Sarawak, British North Borneo, Palawan, and other neighbouring islands?, Proceedings of the Zoological Society of London, vol. 1895, pp. 97?127, 1895.