Columbia subject headings:
Harvard subject headings:
Boundary disputes--History--Congresses.
Civilization, Medieval--Congresses
Feudalism--Europe--History--Congresses.
Vendetta--Europe--History--Congresses.
Vendetta--Europe--History--To 1500--Congresses.
Violence--Europe--History--Congresses.
Violence--Europe--History--To 1500--Congresses.
Princeton subject headings:
Boundary disputes--History--Congresses.
Vendetta--Europe--History--Congresses.
Violence--Europe--History--Congresses.