Columbia subject headings:
Coal mines and mining--England--Derbyshire--History.
Coal mines and mining--England--Leicestershire--History.
Harvard subject headings:
Coal trade--England--Leicestershire--History.
Coal trade--England--South Derbyshire--History.
Industries--England--Leicestershire--History.
Industries--England--South Derbyshire--History.
Princeton subject headings:
Coal mines and mining--England--Derbyshire--History.
Coal mines and mining--England--Leicestershire--History.