1. V. I. Litvinenko, N. P. Maksyutina, and D. G. Kolesnikov, Med. Prom., No. 3, 40 (1962).
2. V. I. Litvinenko and N. P. Maksyutina, Khim. Prirodn. Soedin., 420 (1965).
3. D. A. Murav'eva, Author's Abstract of Doctoral Dissertation [in Russian] (1965).
4. E. T. Bryant, J. Amer. Chem. Soc. Sci.,39, 8, 480 (1950).
5. L. Hórhammer and K. H. Múller, Arch. Pharm.,287, 310 (1954).