Columbia subject headings:
Harvard subject headings:
Bologna (Italy : Province)--Economic conditions--20th century.
Bologna (Italy : Province)--History--20th century.
Bologna (Italy : Province)--Politics and government--20th century.
Bologna (Italy : Province)--Rural conditions.
Bologna (Italy : Province)--Social conditions--20th century.
Regional planning--Italy--Bologna (Province)--History--20th century.
Princeton subject headings:
Agriculture--Italy--Bologna (Province)--History--20th century.
Bologna (Italy : Province)--Economic conditions--20th century.
Bologna (Italy : Province)--Politics and government--20th century.
Bologna (Italy : Province)--Social conditions--20th century.