Columbia subject headings:
Harvard subject headings:
Agricola, Georg, 1494-1555. De re metallica--Congresses.
Coal--Germany--History--Congresses.
Lignite industry--Germany--History--Congresses.
Lignite--Germany--History--Congresses.
Princeton subject headings:
Agricola, Georg, 1494-1555. De re metallica--Congresses.
Coal--Germany--History--Congresses.
Lignite industry--Germany--History--Congresses.
Lignite--Germany--History--Congresses.