Columbia subject headings:
Phenomenology--History--20th century--Sources.
Philosophers--Germany--Biography--Sources.
Philosophers--Germany--History--20th century--Sources.
Philosophy, German--20th century--Sources.
World War, 1914-1918--Germany--Sources.
Harvard subject headings:
Philosophers--Germany
Philosophy, German--20th century--Sources.
World War, 1914-1918--Germany--Sources.
Princeton subject headings:
Philosophers--Germany.
Philosophy, German--20th century--Sources.
World War, 1914-1918--Germany--Sources.