Enneagram system for personal development series
For anyone who is a person, a parent, a coach, a colleague, a boss, a leader, a thinker, an entrepreneur, a peacemaker, a lover, a member of society

Notabe authors are
Naranjo (pioneer, so all the ideas have not yet been synthesized well)
Riso and Hudson (the authors who really started the watershed event)
Virginia Price
Palmer

I have not had time to read the others, but the noscripts seem compelling read.