Columbia subject headings:
Coal mines and mining--Germany.
Forced labor--Germany.
World War, 1914-1918--Germany.
World War, 1939-1945--Germany.
Harvard subject headings:
Coal miners--Germany--History.
Coal mines and mining--Germany
Forced labor--Germany
World War, 1914-1918--Germany.
World War, 1939-1945--Germany.
Princeton subject headings:
Coal miners--Germany--History.
Forced labor--Germany.
World War, 1914-1918--Conscript labor--Germany.
World War, 1939-1945--Conscript labor--Germany.