R.  Tate and Woodward, S. Peckworth, Appendix to the Manual of Mollusca of S.P. Woodward, A.L.S. :. London :Virtue & Yorston, 1868, p. 106.

S. Peckworth Woodward, The life of the Mollusca. London,Methuen & Co., 1913, p. 182.