Baum, W. M. 1979 Matching, undermatching, and overmatching in studies of choice. Journal of the Experimental Analysis of Behavior, 32, 269-281.
Chung, S. H. 1965 Effect of effort on response rate. Journal of the Experimental Analysis of Behavior, 8, 1-7.
de Villiers, P. A., & Millenson, J. R. 1972 Concurrent performances: A baseline for the study of conditioned anxiety. Journal of the Experimental Analysis of Behavior, 18, 287-294.
Fantino, E. 1969 Choice and rate of reinforcement. Journal of the Experimental Analysis of Behavior, 12, 723-730.
Fleshler, M., & Hoffman, H. S. 1962 A progression for generating variable-interval schedules. Journal of the Experimental Analysis of Behavior, 5, 529-530.