Columbia subject headings:
Harvard subject headings:
Merchant marine--Spain--País Vasco.
País Vasco (Spain)--History, Naval.
Shipping--Spain--País Vasco--History.
Princeton subject headings:
Commerce--History--Medieval, 500-1500.
Maritime law--Europe--History.
Merchant marine--Spain--País Vasco--History.
Navies--Spain--País Vasco--History.
País Vasco (Spain)--Commerce--History.
País Vasco (Spain)--History, Naval.
Shipping--Spain--País Vasco--History.