Columbia subject headings:
Harvard subject headings:
Baltic Sea Region--Commerce--Portugal--History.
Commerce--History--Medieval, 500-1500
Hanseatic League--History.
Portugal--Commerce--Baltic Sea Region--History.
Princeton subject headings:
Baltic Sea Region--Commerce--Portugal--History.
Commerce--History--Medieval, 500-1500.
Hanseatic League--History.
Portugal--Commerce--Baltic Sea Region--History.