Cita APA (7th ed.)

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

Cita Chicago (17th ed.)

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

Cita MLA (9th ed.)

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