1. M. N. Shchukina, Med. Prom. SSSR, No. 7, 42 (1957).
2. A. McLean, J. Habeshaw, W. Oldham et al., Brit. Pat. No. 781454 (1957)
3. Ref. Zh. Khimiya, No. 17, No. 61740P (1959).
4. J. Charles, Brit. Pat. No. 772443 (1957); Chem. Abs.,51, 14811 (1957).
5. I. Ken-ichi Watanabe, Bull. Chem. Soc. Japan,32, 1280 (1959); Ref. Zh. Khimiya, No. 18, No. 73308 (1960).