Columbia subject headings:
Opera--19th century.
Wagner, Richard, 1813-1883--Criticism and interpretation.
Harvard subject headings:
Opera--19th century
Wagner, Richard, 1813-1883
Wagner, Richard, 1813-1883--Criticism and interpretation.
Princeton subject headings:
Wagner, Richard, 1813-1883--Dramaturgy.
Wagner, Richard, 1813-1883. Literary works. Selections. English