1. Paton, W. D.M., J. Pharmac., 11, 119 (1957).
2. Schaumann, W., Brit. J. Pharmac., 12, 115 (1957).
3. Kosterlitz, H. W., and Robinson, J. A., Br. J. Pharmac., 13, 296 (1958).
4. Gyang, A. E., and Kosterlitz, H. W., Br. J. Pharmac., 27, 514 (1966).
5. Ehrenpreis, S., Light, I., and Schonbuch, G. H., in Drug Addiction: Experimental Pharmacology (edit, by Singh, J. M., Miller, L. H., and Lai, H.), 319 (Futura, Mt Kisco, New York, 1972).