Columbia subject headings:
Commerce--History--Medieval, 500-1500.
Europe--Commerce--History--To 1500.
Merchants--Europe--History--To 1500.
Harvard subject headings:
Commerce--History--Medieval, 500-1500
Europe--Commerce--History--To 1500.
Merchants--Europe--History--To 1500.
Princeton subject headings:
Commerce--History--Medieval, 500-1500.
Merchants--Europe--History--To 1500.