Columbia subject headings:
Harvard subject headings:
Europe--Politics and government--Congresses.
Germany--Politics and government--Congresses.
Internal security--Europe--History--Congresses.
Internal security--Germany--History--Congresses.
International relations--Congresses
Social security--Europe--History--Congresses.
Princeton subject headings:
International law--Congresses.
International relations--Congresses.
Security, International--Congresses.