1. G. Galilei, Il Saggiatore, vol. 6 (Edition Nationale, Florence, Italy, 1896), p. 232. English translation from Italian original
2. C. Darwin, On the Origin of Species by Means of Natural Selection or the Preservation of Favoured Races in the Struggle for Life (John Murray, London, 1859)
3. E. Mayr, The Growth of Biological Thought. Diversity, Evolution, and Inhertiance (The Belknap Press of Harvard University Press, Cambridge, MA, 1982)
4. R.A. Fisher, The Genetical Theory of Natural Selection (Oxford University Press, Oxford, 1930)
5. J.B.S. Haldane, The Causes of Evolution (Longmans Green, London, 1932). Reprinted 1990 in the Princeton Science Library by Princeton University Press, Princeton, NJ