1. Thoday, J. M., Symp. Soc. exp. Biol., 7, 96–113 (1953).
2. Thoday, J. M., in A Century of Darwin (edit. by Barnett, S. A.), 313–333 (Heinemann, London, 1958).
3. Huxley, J., Evolution (Allen and Unwin, London, 1942).
4. Huxley, J., Evolution and Ethics (Pilot Books, New York, 1947).
5. Stebbins, G. L., The Basis of Progressive Evolution (University of North Carolina Press, Chapel Hill, 1969).