1. Van Rossum, J. M., Arch. int. Pharmacodyn., 160, 492–494 (1966).
2. Iversen, L. L., Science, 188, 1084–1089 (1975).
3. Horn, A. S., Post, M. L., and Kennard, O., J. Pharm. Pharmac., 27, 553–563 (1975).
4. Matthysse, S., Fedn Proc., 32, 200–204 (1973).
5. Seeman, P., Wong, M., and Lee, T., Fedn Proc., 33, 246 (1974).