Cita APA (7a ed.)

Webb, K. (2012). Principles of the Enneagram (2nd ed.). Jessica Kingsley Publishers.

Cita Chicago Style (17a ed.)

Webb, Karen. Principles of the Enneagram. 2nd ed. London: Jessica Kingsley Publishers, 2012.

Cita MLA (8a ed.)

Webb, Karen. Principles of the Enneagram. 2nd ed. Jessica Kingsley Publishers, 2012.