Columbia subject headings:
Harvard subject headings:
Peace movements--History--20th century--Congresses.
World War, 1914-1918--Peace--Congresses.
World War, 1914-1918--Protest movements--Congresses.
Princeton subject headings:
Mühsam, Erich, 1878-1934--Congresses.
Peace movements--Europe--History--Congresses.
Peace--Societies, etc.--Congresses.
World War, 1914-1918--Protest movements--Congresses.