1. Are theories of learning necessary?;Skinner;Psychol Rev,1950
2. Relational discrimination learning in pigeons;Cook,2012
3. Pigeon same different concept learning with multiple stimulus classes;Cook;J Exp Psychol: Anim Behav Processes,1997
4. Pictorial same-different categorical learning and concept learning by pigeons;Cook;J Exp Psychol: Anim Behav Processes,1999