1. Isolation of an internal clock;Roberts;Journal of Experimental Psychology: Animal Behavior Processes,1981
2. Cross-modal use of an internal clock;Roberts;Journal of Experimental Psychology: Animal Behavior Processes,1982
3. Timing light and tone signals in pigeons;Roberts;Journal of Experimental Psychology: Animal Behavior Processes,1989
4. Proactive effects in pigeons' timing behavior: Implications for an internal-clock model;Wilkie;Animal Learning & Behavior,1988