Columbia subject headings:
Harvard subject headings:
Europe--Kings and rulers--Congresses.
Kings and rulers in art--Congresses.
Kings and rulers in literature--Congresses.
Kings and rulers, Medieval--Congresses.
Kings and rulers--Health and hygiene--Congresses.
Political culture--Europe--Congresses.
Princeton subject headings:
Europe--Kings and rulers--History--To 1500.
Power (Social sciences)--Europe--History--To 1500.
Sovereignty--History--To 1500.