Columbia subject headings:
Wagner, Richard, 1813-1883--Criticism and interpretation--Congresses.
Wagner, Richard, 1813-1883. Ring des Nibelungen--Congresses.
Harvard subject headings:
Operas--Analysis, appreciation
Wagner, Richard, 1813-1883. Ring des Nibelungen.
Princeton subject headings:
Operas--Analysis, appreciation.
Wagner, Richard, 1813-1883. Ring des Nibelungen.