Published recently by H. Tsiamoulis a theory of traditional music entitled "Numerical modal system." It is a book that presents the history of musical tradition and presents the material: musical modes, rhythms, harmonic accompaniment, etc., bridging the two major traditions of tropical music: sounds of church and eastern maqam. Publications Papagrigoriou - Nakas, Penepistimiou 39 (www.panasmusic.gr)