C.  Darwin and Wallace, A. Russel, ?On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection?, Journal of the Proceedings of the Linnean Society: Zoology, vol. 3, pp. 45-62, 1858.

A. Russel Wallace, ?On the phenomena of variation and geographical distribution as illustrated by the Papilionidae of the Malayan region.?, Transactions of the Linnean Society of London, vol. 25, no. 1, pp. 1?71, 1865.