1. Dahlgren, R., Bot. Not. 128:119 (1975).
2. Kjær, A., in “The Chemistry of Organic Natural Products,” edited by L. Zechmeister, Springer-Verlag, Berlin and New York, 1960, p. 122.
3. Ettlinger, M.G., and A. Kjær, in “Recent Advances in Phyto- chemistry,” Vol. 1, edited by T.J. Mabry, R.E. Alston and V.C. Runeckles, Appleton-Century-Crofts, New York, 1968, p. 59.
4. Kjær, A., and P.O. Larsen, in “Biosynthesis,” Vol. 2, edited by T.A. Geissmann, Specialist Periodical Reports, The Chem- ical Society, London, 1973, p. 71.
5. Underhill, E.W., L.R. Wetter and M.D. Chisholm, in “Nitrogen Metabolism in Plants,” edited by T.W. Goodwin and R.M.S. Smellie, Biochemical Society Symposium No. 38, Biochemical Society, London, 1973, p. 303.