JAMMERS, Ewald. Gregorianische Studien. Die Musikforschung, [S. l.], v. 5, n. 1, p. 24–37, 1952. DOI: 10.52412/mf.1952.H1.2782. Disponível em: https://mf.journals.qucosa.de/mf/article/view/2782. Acesso em: 10 mai. 2025.