Columbia subject headings:
Harvard subject headings:
Coal mines and mining--Germany--Saarbrücken--History.
Industries--Social aspects--Germany--Saarbrücken.
Saarbergwerke--History.
Princeton subject headings:
Coal mines and mining--Germany--Saabrücken--History.
Industries--Social aspects--Germany--Saarbrücken.
Saarbergwerke--History.