Columbia subject headings:
Harvard subject headings:
Nobility--Italy--Po River Valley--History.
Nobility--Italy--Po River Valley--Portraits.
Po River Valley (Italy)--History--Pictorial works.
Po River Valley (Italy)--History.
Princeton subject headings:
Nobility--Italy--Po River Valley--History.
Nobility--Italy--Po River Valley--Portraits.
Po River Valley (Italy)--History--Pictorial works.
Portraits.