1. Leperchey, F. & Barbet, J.P. Morphologie 82, 19–28 (1998).
2. Waddington, C.H. Endeavour 1, 18–20 (1942).
3. Waddington, C.H. An Introduction to Modern Genetics 154–156 (Allen & Unwin, London, 1939).
4. Robertson, A. Biogr. Mem. Fellows R. Soc. 23, 575–622 (1977).
5. Berger, S.L. et al. Genes Dev. 23, 781–783 (2009).