Columbia subject headings:
Authors, German--20th century--Biography.
Keller, Paul, 1873-1932.
Harvard subject headings:
Authors, German--20th century--Biography
Keller, Paul, 1873-1932.
Princeton subject headings:
Authors, German--19th century--Biography.
Authors, German--20th century--Biography.
Keller, Paul, 1873-1932.