Fundamentals of Gregorian Chant - Dominic Keller - OS Justi Press (Paperback)ByDominic Keller.This handy 80-page guide to the Solesmes method of singing Gregorian chant is commendable as a pedagogical tool and a resource for choirs and scholas. Its principal virtues are the clarity of explanation, the excellent examples, and the exercises.See a photo and table of contentshere.