Carpio, C., V. Pacheco, G. Gutiérrez, R. Hernández, and E. Ribes. “Probability and Availability of Reinforcement in Temporal Schedules of Different Durations”. Mexican Journal of Behavior Analysis, vol. 15, no. 1y2, Jan. 2011, pp. 67-87, doi:10.5514/rmac.v15.i1y2.23469.