Hermann Keller is a musicologist who has held important posts as an organist and taught for many years at the Württemberg Conservatory of Music. His books include Thoroughbass Method and Phrasing and Articulation. Until his death in 1965, Carl Parrish was professor at Vassar College. He was the author of The Notation of Medieval Music, and editor of Masterpieces of Music Before 1750 (with John F. Ohl) and A Treasury of Early Music. Until his death in 1965, Carl Parrish was professor at Vassar College. He was the author of The Notation of Medieval Music, and editor of Masterpieces of Music Before 1750 (with John F. Ohl) and A Treasury of Early Music.