Keller, Fred Simmons, 1899- Learning : Reinforcement theory / [By] Fred S. Keller. - New York : Random House, [1965]. - 36 p. : ill. - A Random House study in psychology PP13 . - 153.1/5 . Bibliogr.: p. 81. Subjects--Topical Terms: Learning, Psychology of. Dewey Class. No.: 153.1/5