1. M. J. Kornet and J. Y-R. Chu, J. Pharm. Sci., in press and references cited therein.
2. F. K. Kirchner and A. W. Zalay, U. S. 3,217,005 (1965)
3. Chem. Abstr., 64, 3570 (1966).
4. H. Herlinger, S. Petersen, E. Tietze, F. Hoffmeister, and W. Wirth, Belgian Patent 614,243 (1962)
5. Chem. Abstr., 61, 4585 (1963).