Columbia subject headings:
Harvard subject headings:
Mine drainage--Germany--Clausthal-Zellerfeld--History.
Mine drainage--Germany--Oberharz Mountains--History.
Mine water--Germany--Clausthal-Zellerfeld--History.
Mine water--Germany--Oberharz Mountains--History.
Mineral industries--Germany--Clausthal-Zellerfeld--History.
Mineral industries--Germany--Oberharz Mountains--History.
Mines and mineral resources--Germany--Clausthal-Zellerfeld--History.
Mines and mineral resources--Germany--Oberharz Mountains--History.
Princeton subject headings:
Mines and mineral resources--Germany--Harz Mountains Region.
Silver mines and mining--Germany--Harz Mountains Region.