Columbia subject headings:
Cities and towns--Italy--Po River Plain--Growth.
Po River Plain (Italy)--Social conditions.
Urbanization--Italy--Po River Plain.
Harvard subject headings:
Cities and towns--Italy--Po River Plain--Growth.
Metropolitan areas--Italy--Po River Plain.
Urbanization--Italy--Po River Plain.
Princeton subject headings:
Cities and towns--Italy--Po River Plain--Growth.
Metropolitan areas--Italy--Po River Plain.
Urbanization--Italy--Po River Plain.