1. D. H. R. Barton and C. R. Narayanan, J. Chem. Soc., 963 (1958).
2. L. Dolej?, M. Sou?ek, M. Horak, V. Herout, and F. ?orm, Coll. Czech. Chem. Commun.,23, 2195 (1958).
3. Flora of Turkmenia [in Russian], Ashkhabad, Vol. 7 (1960).
4. H. Budzicievicz, J. M. Wilson, and C. Djerassi, J. Am. Chem. Soc.,75, 2677 (1963).
5. T. K. Devon and A. I. Scott, Handbook of Naturally Occurring Compounds, Academic Press, New York, Vol. II (1972).