Columbia subject headings:
Harvard subject headings:
Coal mines and mining--Silesia, Upper (Poland and Czech Republic)
Silesia, Upper (Poland and Czech Republic)
World War, 1914-1918--Territorial questions--Silesia, Upper (Poland and Czech Republic)
Princeton subject headings:
Coal mines and mining--Silesia.
Silesia.
World War, 1914-1918--Territorial questions--Silesia.