Columbia subject headings:
Harvard subject headings:
Berio, Luciano, 1925-2003. Operas.
Dallapiccola, Luigi, 1904-1975. Ulisse.
Libretto--20th century.
Nono, Luigi. Prometeo
Opera--Italy--20th century--Philosophy and aesthetics.
Princeton subject headings:
Libretto.
Music theater--Italy--20th century--History and criticism.