1. P. M. Kochergin, L. S. Blinova, R. M. Titkova, et al., Med. Prom. SSSR, No. 6, 22 (1958).
2. I. B. Cohen and W. H. Harrison, J. Chem. Soc.,71, 1057 (1897).
3. B. O. Fried and L. J. Crundy, J. Chem. Soc., 1110 (1955).
4. B. Helferich, R. Streeck, and E. Gunther, J. Prakt. Chem.,151, 251 (1938).
5. W. Krauss and H. Ohle, DDR Pat. No. 9,912 and 10,146; Ref. Zh. Khimiya, No. 2, 5768P, 5769P (1957).