Columbia subject headings:
Verdi, Giuseppe, 1813-1901--Criticism and interpretation--Congresses.
Verdi, Giuseppe, 1813-1901. Rigoletto--Congresses.
Verdi, Giuseppe, 1813-1901. Traviata--Congresses.
Verdi, Giuseppe, 1813-1901. Trovatore--Congresses.
Harvard subject headings:
Princeton subject headings:
Opera--Italy--19th century.
Verdi, Giuseppe, 1813-1901--Criticism and interpretation.
Verdi, Giuseppe, 1813-1901. Rigoletto.
Verdi, Giuseppe, 1813-1901. Traviata.
Verdi, Giuseppe, 1813-1901. Trovatore.