Cita APA (7a ed.)

Spencer, H. (1899). The principles of psychology (4a ed.). Williams and Norgate.

Cita Chicago Style (17a ed.)

Spencer, Herbert. The Principles of Psychology. 4a ed. London: Williams and Norgate, 1899.

Cita MLA (9a ed.)

Spencer, Herbert. The Principles of Psychology. 4a ed. Williams and Norgate, 1899.