1. Carlquist S. (1965) Island life. Natural History Press, New York.
2. Clarke B. (1966) The evolution of morph-ratio clines. Am. Nat. 100, 389–402.
3. Clarke B. (1968) Balanced polymorphism and regional differentiation in land snails. In E. T. Drake (ed.), Evolution and Environment, pp. 351-368. Yale University Press.
4. Clarke B. & Murray J. (1969) Ecological genetics and speciation in land snails of the genus Partula. Biol. J. Linn. Soc. 1, 31–42.
5. Crampton H. E. (1932) Studies on the variation, distribution, and evolution of the genus Partula. The species inhabiting Moorea. Pubis Carnegie Instn 410, 1–335.