1. A. V. Kamernitskii, L. E. Kulikova, I. S. Levina, and V. B. Muratov, Izv. Akad. Nauk SSSR, Ser. Khim.,1976, 1129.
2. F. Winternitz and C. R. Engel, Steroids,6, 805 (1966).
3. A. A. Akhrem, A. V. Kamernitskii, and A. V. Skorova, USSR Patent 380,649 (1971);
4. Byull. Izobr., No. 21 (1973).
5. G. Drefahl, K. Ponseld, and B. Schönecker, Z. Chem.,5, 268 (1965).