D. C. Williams, Y. Hayashi, A. Brewer, K. J. Saunders, S. Fowler, and R. C. Pitts, “Transitions from Rich-to-Lean Schedules Increase Attack in a Laboratory Model of Social Aggression in Pigeons: I. Fixed-Ratio Schedules”, MJBA, vol. 45, no. 2, Dec. 2019.