The first of these, in Italian, was "Le regole più necessarie per l'introduzione del canto fermo", which he published in 1609. It was a didactic and practical work on singing plainsong, which he probably used in his work at the Neapolitan church of Ss Annunziata. Four years later, however, he published a monumental volume on music theory, "El melopeo y maestro: tractado de música theorica y pratica; en que se pone por extenso; lo que uno para hazerse perfecto musico ha menester saber", which consisted of 22 volumes, 849 chapters, and 1160 pages in the original Spanish.