Columbia subject headings:
Harvard subject headings:
Coal mines and mining, Prehistoric--Germany--Essen.
Essen (Germany)--Antiquities.
Mine lighting--Germany--Essen--History.
Mineral industries--Germany--Essen--History.
Safety lamps--Germany--Essen--History.
Princeton subject headings:
Archaeology and history--Germany--Essen.
Excavations (Archaeology)--Germany--Essen.
Industrial archaeology--Germany--Essen.
Mines and mineral resources--Germany--Essen.