Columbia subject headings:
Ambassadors--History--Congresses.
Diplomatic negotiations in international disputes--History--Congresses.
Europe--Diplomatic history--Congresses.
Harvard subject headings:
Ambassadors--History--Congresses.
Diplomatic negotiations in international disputes--History--Congresses.
Europe--Diplomatic history--Congresses.
Princeton subject headings:
Diplomacy--History.
Diplomatic etiquette--History.
Diplomats--History.