1. Doyle, J. A. & Hickey, L. J. in Origin and Early Evolution of Angiosperms (ed. Beck, C. B.) 139–206 (Columbia University Press, New York, 1976).
2. Hughes, N. F. Bot. Rev. 43, 105–127 (1977).
3. Hickey, L. J. & Doyle, J. A. Bot. Rev. 43, 3–104 (1977).
4. Beck, C. B. (ed.) Origin and Early Evolution of Angiosperms, 1–341 (Columbia University Press, New York, 1976).
5. Kemp, E. M. Palaeontology 11, 421–434 (1968).