Keller, Fred S. 1899-1996. Principles of psychology : a systematic text in the science of behavior / Fred S. Keller and William N. Schoenfeld. - New York : Appleton-Century-Crofts , 1950 - xv, 431 p. : diagrs. 22 cm. - The Century psychology series . Bibliography: p. 403-420. Subjects--Topical Terms: Psychology. Dewey Class. No.: 150 / KEP 1950