Columbia subject headings:
Nietzsche, Friedrich Wilhelm, 1844-1900.
Wagner, Richard, 1813-1883.
Harvard subject headings:
Nietzsche, Friedrich Wilhelm, 1844-1900
Nietzsche, Friedrich Wilhelm, 1844-1900. Correspondence
Wagner, Richard, 1813-1883
Wagner, Richard, 1813-1883. Correspondence
Princeton subject headings:
Composers--Germany--Correspondence.
Nietzsche, Friedrich Wilhelm, 1844-1900.
Philosophers--Germany--Correspondence.
Wagner, Richard, 1813-1883.