Sorry to take so long in answering.
I've read a number of the Enneagram books available, but most of my study was with my roommate at the time, who was on his way to certification in Don Riso's program for Enneagram teachers. So I tend to see it from his viewpoint, though I don't try to discuss all of his details, like the levels of health. I can recommend A.H. Almaas's book on the Enneagram without reservation.
I typed Roger Waters myself, based on the volume of lyrics he has written for Pink Floyd and elsewhere.