Palisca, Claude V. Grout, Donald Jay, 1902-1987 History of western music. Euripides, v480-v407 Orestes. Selections. Wipo, active 11th century. Victimae paschali laudes. Hildegard, Saint, 1098-1179. Ordo virtutum. In principio omnes.

Cary, M. (Max), 1881-1958. Gardner, Percy, 1846-1937, Gardner, Ernest Arthur, 1862-1939, JSTOR (Organization) Society for the Promotion of Hellenic Studies (London, England)