Columbia subject headings:
Harvard subject headings:
Disaster relief--Italy--Po River Plain--History--Congresses.
Floods--Italy--Po River Plain--History--Congresses.
Po River Plain (Italy)--History--Congresses.
Princeton subject headings:
Disaster relief--Italy--Po River Plain--History--Congresses.
Floods--Italy--Po River Plain--History--Congresses.
Po River Plain (Italy)--History--Congresses.