Columbia subject headings:
Harvard subject headings:
Heads of state--Succession--History--Congresses.
Kings and rulers--Congresses.
Royal houses--History--Congresses.
Princeton subject headings:
Civilization, Medieval--Congresses.
Europe--Kings and rulers--Genealogy--Congresses.
Heads of state--Succession--History--Congresses.
Kings and rulers--Congresses.
Royal houses--History--Congresses.