APA aipamena

Riso, D. R., & Hudson, R. (2000). Understanding the enneagram: The practical guide to personality types (Rev. ed.). Houghton Mifflin.

Chicago Style aipamena

Riso, Don Richard, and Russ Hudson. Understanding the Enneagram: The Practical Guide to Personality Types. Rev. ed. Boston: Houghton Mifflin, 2000.

MLA aipamena

Riso, Don Richard, and Russ Hudson. Understanding the Enneagram: The Practical Guide to Personality Types. Rev. ed. Houghton Mifflin, 2000.