Columbia subject headings:
Harvard subject headings:
Fell (Germany)--History.
Mines and mineral resources--Germany--Fell--History.
Mines and mineral resources--Germany--Thomm--History.
Slate industry--Germany--Fell--History.
Slate industry--Germany--Thomm--History.
Thomm (Germany)--History.
Princeton subject headings:
Fell (Germany)--History.
Mines and mineral resources--Germany--Fell--History.
Mines and mineral resources--Germany--Thomm--History.
Thomm (Germany)--History.