Columbia subject headings:
Operas--Librettos.
Wagner, Richard, 1813-1883. Ring des Nibelungen. Rheingold.
Harvard subject headings:
Operas--Librettos
Wagner, Richard, 1813-1883. Ring des Nibelungen. Rheingold.
Princeton subject headings:
Librettos.
Operas--Librettos.
Wagner, Richard, 1813-1883. Ring des Nibelungen. Rheingold