1. W. Langenbeck, Organic Catalysts [Russian translation], IL (1961), p. 43.
2. W. Dethloff and H. Mix, Chem. Ber.,82, 534 (1949).
3. H. Mix, Ann. Chem.,592, 146 (1955).
4. S. Somasekhara, V. S. Dighe, G. K. Suthar, and S. L. Mukherjee, Current Sci.,34, 508 (1965).
5. W. Franke, Biochem. Z.,258, 295 (1933).