Cita APA (7th ed.)

Spencer, H. (1970). The principles of psychology. Gregg International Publishers Limited.

Cita Chicago (17th ed.)

Spencer, Herbert. The Principles of Psychology. Farnham: Gregg International Publishers Limited, 1970.

Cita MLA (9th ed.)

Spencer, Herbert. The Principles of Psychology. Gregg International Publishers Limited, 1970.