Columbia subject headings:
Harvard subject headings:
Italy--Commerce--Portugal--History.
Portugal--Commerce--Italy--History.
Portugal--Commerce--Italy--Sicily--History.
Sicily (Italy)--Commerce--Portugal--History.
Princeton subject headings:
Algarve (Portugal)--Commerce--History.
Fish trade--Portugal--Algarve--History.
Italians--Commerce--Portugal--Algarve--History.
Portugal--Commercial policy--History.
Sicily (Italy)--Commerce--History.
Sicily (Italy)--Foreign economic relations--Portugal.