1. Landmesser, L. & Lance-Jones, C. in Development in the Nervous System (eds Garrod, D. R. & Feldman, J. D.) 215–231 (Cambridge University Press, 1981).
2. Hamburger, V. & Hamilton, H. L. J. Morphol. 88, 49–92 (1951).
3. Tello, J. F. Trav. Lab. Invest. biol. Univ. Madr. 21, 1–93 (1923).
4. Detwiler, S. R. J. exp. Zool. 67, 395–441 (1934).
5. Lewis, J., Chevallier, A., Kieny, M. & Wolpert, L. J. Embryol. exp. Morph. 64, 211–232 (1981).