Columbia subject headings:
Harvard subject headings:
Communists--Germany--Correspondence.
Duncker, Hermann--Correspondence.
Duncker, Käte--Corresondence.
Soldiers--Germany--Correspondence
World War, 1914-1918--Personal narratives, German
World War, 1914-1918--Protest movements--Germany.
Princeton subject headings:
Communists--Germany--Correspondence.
Duncker, Hermann--Correspondence.
Duncker, Käte--Corresondence.
Soldiers--Germany--Correspondence.
World War, 1914-1918--Personal narratives, German.
World War, 1914-1918--Protest movements--Germany.