1. Allsopp, A. (1969). New Phytol., 68, 591.
2. Carr, N. G. and Craig, I. (1970) in Phylogenetic Aspects of Phytochemistry, (Academic Press, New York and London).
3. Chadefaud, M. (1963). Revue Algol, N.S. 6, 255.
4. Chapman, V. J. (1954). Bull. Torrey bot. Club, 81, 76.
5. Chapman, D. J. and V. J. (1961). Ann. Bot., N.S., 25, 547.