Ed. de Coussemaker: Les harmonistes des XIIme et XIIIme siècles (Lille, 1864).
Ed. de Coussemaker: L'Art harmonique au XIIme et XIIIme siècles (Paris, 1865).
Ed. de Coussemaker: Histoire de l'harmonie au moyen-âge (1852).
In Italian
L. Angelini: Sopra la vita ed il sapere di Guido d'Arezzo (1811).
Guido Gasperini: Storia della semiografia musicale (1905).
LITERATURE FOR CHAPTER VII
In English
Edmondstoune Duncan: Story of Minstrelsy.
Edward Jones: Musical and Poetical Relicks of the Welsh Bards (three parts, 1786, 1802, 1824).