APA (7th ed.) Citation

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

Chicago Style (17th ed.) Citation

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

MLA (9th ed.) Citation

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

Warning: These citations may not always be 100% accurate.