Columbia subject headings:
Opera--Dramaturgy.
Opera.
Wagner, Richard, 1813-1883--Dramaturgy.
Wagner, Richard, 1813-1883. Operas.
Harvard subject headings:
Opera
Opera--Dramaturgy
Wagner, Richard, 1813-1883--Dramaturgy.
Wagner, Richard, 1813-1883. Operas
Princeton subject headings: