1. Janssen, P.: Pharmacologie comparee du haloperidol et du triperidol. Encephale 51, 582?601 (1962)
2. Leuba, C.: Towards some integration of learning theories: the concept of optimum stimulation. Psychol. Rep. 1, 27?33 (1955)
3. Lowe, G.: The objective assessment of hallucinogenic drug effects in animals. International Research Communications System (73-12) (1973)
4. Lowe, G., Williams, d. I.: An arousal model of sensory reinforcement. Bull. Brit. Psychol. Soc. 21, 119 (1968)
5. Lowe, G., Williams, D. I.: Differential reinforcing effects of steady and flickering light on bar pressing in the rat. Psychon. Sci. 15, 231?232 (1969)