Columbia subject headings:
Calumet and Hecla Mining Company.
Copper Miners' Strike, Mich., 1913-1914.
Copper mines and mining--Michigan.
International Union of Mine, Mill, and Smelter Workers.
Harvard subject headings:
Calumet and Hecla Consolidated Copper Company.
Copper Miners' Strike, Mich., 1913-1914.
Copper mines and mining--Michigan
International Union of Mine, Mill, and Smelter Workers.
Princeton subject headings: