| title | ISBN-13 (ISBN-10) | year of publica- tion | other author(s) |
|---|---|---|---|
| Enneagram | 978-0-7153-2837-8 (0-7153-2837-9) | 2007 | John Waters |
| Everything Enneagram Book: Identify Your Type, Gain Insight into Your Personality and Find Success in Life, Love, and Business | 978-1-59869-276-1 (1-59869-276-3) | 2007 | Susan Reynolds |
P R · R. P. · R.R. · R. Ritchie · Ronna Phifer-Ritchie Ph.D