1. Bremner, F. J., Cobb, H. W., Hahn, W. C.: The effects of chlordiazepoxide on the behavior of rats in a conflict situation. Psychopharmacologia (Berl.) 17, 275?282 (1970).
2. Davis, J. P., Miller, N. E.: Fear and pain: Their effect on self-injection of amobarbital sodium by rats. Science 141, 1287?1288 (1963).
3. Deneau, G. A.: Drug self-administration by monkeys. In: H. Steinberg (Ed.): Scientific Basis of Drug Dependence. London: J. H. Churchill 1968.
4. ?, Yanagita, T., Seevers, M. H.: Psychic dependence studies of self-administration techniques in Rhesus monkeys. Comm. Drug Addiction and Narcotics, NRC-NAS, Houston, Texas (1965).
5. Findley, J. D., Robinson, W. W.: Aversive preference as a function of fixed-ratio requirements. East. Psychol. Ass. (N. Y.) (1971).