Columbia subject headings:
Commerce--History--Medieval, 500-1500.
Europe--Commerce--History.
Frisians--History.
Merchants--Netherlands--Friesland--History.
Trade routes--Europe--History.
Harvard subject headings:
Commerce--History--Medieval, 500-1500
Europe--Commerce--History.
Frisians--History.
Merchants--Netherlands--Friesland--History.
Trade routes--Europe--History.
Princeton subject headings:
Commerce--History--Medieval, 500-1500.
Europe--Commerce--History.
Frisians--History.
Merchants--Netherlands--Friesland--History.
Trade routes--Europe--History.