Schoen, D J, Morgan, M T & Bataillon, T 1996, ' How does self-pollination evolve? Inferences from floral ecology and molecular genetic variation ', Philosophical Transactions of the Royal Society B: Biological Sciences, vol. 351, no. 1345, pp. 1281-1290 . https://doi.org/10.1098/rstb.1996.0111