1. K. S. Rybalko, M. N. Mukhametzhanova, V. I. Sheichenko, and O. A. Konovalova, Khim. Prir. Soedin., 467 (1976).
2. J. M. Cassady, M. F. Bean, J. L. McLaughlin, and Y. Aynchchi, Experientia, 40, 930 (1984).
3. S. M. Adekenov, A. T. Kulyyasov, V. A. Raldugin, I. Yu. Bargyanskaya, Yu. V. Gatilov, and M. M. Shakirov, Izv. Akad. Nauk, Ser. Khim., 169 (1998).
4. J. Harmata and Z. Samek, Collect. Czech. Chem. Commun., 47, 2779 (1982).
5. USSR State Pharmacopoeia, 11th Ed., No. 2, Meditsina, Moscow (1989), 210.