1. J. Arditti, Orchid Biology, vol. 1. Cornell University Press, Ithaca and London 1977.
2. J.B. Harborne, Comparative Biochemistry of the Flavonoids, Academic Press, London and New York 1967.
3. J.B. Harborne, T.J. Mabry and H. Mabry, ed., The Flavonoids. Chapman and Hall, London 1975.
4. J. Arditti, Am. J. Bot.56, 59 (1969).
5. R.F. Albach, R.E. Kepner and A.D. Webb, J. Food Sci.30, 69 (1965).