- The Enneagram: Understanding Yourself and the Others In Your Life
- The Enneagram in Love and Work: Understanding Your Intimate and Business Relationships
- The Enneagram Advantage: Putting the 9 Personality Types to Work in the Office
- The Pocket Enneagram: Understanding the 9 Types of people
- Johnny's machines
- Mike McClintock
- Marilyn Sadler
- Joan Heilbroner
- Don Richard Riso
- Michael Frith
- Russ Hudson
- Otto Kroeger
- Janet M. Thuesen
- Rosetta Stone
- Paul B. Brown
- Elizabeth Wagele
- Renee Baron
- Isabel Briggs Myers
- Eric Gurney
- Christopher Moroney
- Andreas Ebert
- Theodore E. Dobson
- Kathleen V. Hurley
- Kathy Hurley
- Peter B. Myers