Columbia subject headings:
Alabama--Economic conditions.
Coal mines and mining--Alabama.
Iron industry and trade--Alabama.
Mines and mineral resources--Alabama.
Harvard subject headings:
Alabama--Economic conditions.
Coal mines and mining--Alabama
Iron industry and trade--Alabama.
Mines and mineral resources--Alabama
Princeton subject headings:
Alabama--Economic conditions.
Coal mines and mining--Alabama.
Iron industry and trade--Alabama.
Mines and mineral resources--Alabama.