1. H. G. Boit, Ergebnise der Alkaloid Chemie bis 1960, Akademie Verlag, Berlin (1961), p. 235.
2. M. Tomita and T. Kugo, Yakugaku Zasshi,77, 1075 (1957); Chem. Abstracts,52, 5429d (1958).
3. A. Karimov, M. V. Telezhenetskaya, K. L. Lutfullin, and S. Yu. Yunusov, Khim. Prirodn. Soedin., 433 (1975)
4. L. P. Naidovich, E. A. Trutneva, O. N. Tolkachev, and V. D. Vasil'eva, Farmatsiya, No. 4, 33 (1975).
5. A. Karimov, M. V. Telezhenetskaya, K. L. Lutfullin, and S. Yu. Yunusov, Khim. Prirodn. Soedin., 558 (1976).