1. The strength of conditioned reinforcers as a function of frequency and probability of reinforcement;Autor,1969
2. Reinforcement schedules: Contingency or contiguity?;Bloomfield,1972
3. Value of knowing when reinforcement is due;Bower;Journal of Comparative and Physiological Psychology,1966
4. Auto-shaping of the pigeon's key-peck;Brown;Journal of the Experimental Analysis of Behavior,1968
5. Concurrent operants;Catania,1966