APA-referens (7:e uppl.)

Spencer, H. (1993). The Principles of Ethics: By Herbert Spencer. Williams and Norgate.

Chicago-referens (17:e uppl.)

Spencer, Herbert. The Principles of Ethics: By Herbert Spencer. London ; Edinburgh: Williams and Norgate, 1993.

MLA-referens (8:e uppl.)

Spencer, Herbert. The Principles of Ethics: By Herbert Spencer. Williams and Norgate, 1993.