1. Barrett JE (1976) Effects of alcohol, chlordiazepoxide, cocaine and pentobarbital on responding maintained under fixed-interval schedules of food or shock presentation. J Pharmacol Exp Ther 196:605?615
2. Barrett JE, Katz JL (1981) Drug effects on behavior maintained by different events. In: Thompson T, Dews PB (eds) Advances in behavioral pharmacology, vol 3. Academic, New York, pp 119?170
3. Barrett JE, Valentine JO, Katz JL (1981) Effects of chlordiazepoxide and d-amphetamine on responding of squirrel monkeys maintained under concurrent or second-order schedules of response-produced food or electric shock presentation. J Pharmacol Exp Ther 219: 199?206
4. Dews PB (1976) Interspecies differences in drug effects: Behavioral. In: Usdin E, Forrest IS (eds) Psychotherapeutic drugs: Principles. Marcel Dekker, New York, pp 175?224
5. Fry W, Kelleher RT, Cook L (1960) A mathematical index of performance on fixed-interval schedules of reinforcement. J Exp Anal Behav 3:193?199