The Enneagram: A systematic review of the literature and directions for future research
Joshua N. Hook; Todd W. Hall; Don E. Davis; Daryl R. Van Tongeren; Mackenzie Conner · 2021 · peer reviewed research
DOI: 10.1002/jclp.23097
Accessed: Jul 15, 2026
The 104-sample review combines heterogeneous instruments and does not validate FermatMind, establish universal nine-factor recovery, or support deterministic individual typing.