APA (7th ed.) Citation

Keller, F. S., & Schoenfeld, W. N. (1950). Principles of psychology: A systematic text in the science of behavior. Appleton-Century-Crofts.

Chicago Style (17th ed.) Citation

Keller, Fred S., and William N. Schoenfeld. Principles of Psychology: A Systematic Text in the Science of Behavior. New York: Appleton-Century-Crofts, 1950.

MLA (9th ed.) Citation

Keller, Fred S., and William N. Schoenfeld. Principles of Psychology: A Systematic Text in the Science of Behavior. Appleton-Century-Crofts, 1950.