REFERENCES
- Baer , D. M. , Wolf , M. M. , & Risley , T. R. ( 1968 ). Some current dimensions of applied behavior analysis . Journal of Applied Behavior Analysis , 1 , 91 – 97 .
- Premack , D. ( 1959 ). Toward empirical behavior laws: I. Positive reinforcement . Psychological Record , 66 , 219 – 233 .