Columbia subject headings:
Harvard subject headings:
Clifton (Ariz.)--History.
Copper mines and mining--Arizona--Clifton--History.
Copper mines and mining--Arizona--Morenci--History.
Morenci (Ariz.)--History.
Strip mining--Arizona--Morenci--History.
Princeton subject headings:
Clifton (Ariz.)--History.
Copper mines and mining--Arizona--Clifton--History.
Copper mines and mining--Arizona--Morenci--History.
Morenci (Ariz.)--History.
Strip mining--Arizona--Morenci--History.