The Theory of Music from the Carolingian Era up to 1400 (5 vols./ 5 Bände) - Vol.I: Descriptive Catalogue of Manuscripts/ Vol.II: Italy/ Vol.III: Manuscripts from the Carolingian Era up to c.1500 in the federal Republic of Germany (D-brd)/ Vol.IV: From the Carolingian Era up to c.1500 in Great Britain and in the USA/ Vol.V: From the Carolingian Era up to c. 1500 in the Czech Republic, Poland, Portugal and Spain