Columbia subject headings:
Coal trade--Saar River Watershed (France and Germany)--History--20th century.
Iron industry and trade--Saar River Watershed (France and Germany)--History--20th century.
Saar River Watershed (France and Germany)--Economic conditions.
Saar River Watershed (France and Germany)--Social conditions.
Steel industry and trade--Saar River Watershed (France and Germany)--History--20th century.
Harvard subject headings:
Coal trade--Saar River Watershed (France and Germany)--History--20th century.
Iron industry and trade--Saar River Watershed (France and Germany)--History--20th century.
Saar River Watershed (France and Germany)--Economic conditions.
Saar River Watershed (France and Germany)--Social conditions.
Steel industry and trade--Saar River Watershed (France and Germany)--History--20th century.
Princeton subject headings:
Coal trade--Saar River Watershed (France and Germany)--History--20th century.
Iron industry and trade--Saar River Watershed (France and Germany)--History--20th century.
Saar River Watershed (France and Germany)--Economic conditions.
Saar River Watershed (France and Germany)--Social conditions.
Steel industry and trade--Saar River Watershed (France and Germany)--History--20th century.