Columbia subject headings:
Harvard subject headings:
Perticara (Italy)--Economic conditions--Congresses.
Società Montecatini--Employees--Economic conditions--Congresses.
Sulfur mines and mining--Italy--Perticara--History--Congresses.
Princeton subject headings:
Perticara (Italy)--Economic conditions.
Perticara (Italy)--History.
Sulfur mines and mining--Italy--Perticara--History.