APA (7th ed.) Citation

Riso, D. R. (1990). Personality types: Using the enneagram for self-discovery. Houghton Mifflin.

Chicago Style (17th ed.) Citation

Riso, Don Richard. Personality Types: Using the Enneagram for Self-discovery. Boston: Houghton Mifflin, 1990.

MLA (8th ed.) Citation

Riso, Don Richard. Personality Types: Using the Enneagram for Self-discovery. Houghton Mifflin, 1990.

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