APA (7th ed.) Citation

Riso, D. R., & Hudson, R. (1996). Personality types: Using the enneagram for self-discovery (Rev. ed.). Houghton Mifflin.

Chicago Style (17th ed.) Citation

Riso, Don Richard, and Russ Hudson. Personality Types: Using the Enneagram for Self-discovery. Rev. ed. Boston: Houghton Mifflin, 1996.

MLA (9th ed.) Citation

Riso, Don Richard, and Russ Hudson. Personality Types: Using the Enneagram for Self-discovery. Rev. ed. Houghton Mifflin, 1996.