Columbia subject headings:
Mexico--History--1867-1910.
Mexico--History--Revolution, 1910-1920.
Mineral industries--Mexico--History.
Mines and mineral resources--Mexico--History.
Harvard subject headings:
Mexico--Economic conditions.
Mineral industries--Mexico--History.
Princeton subject headings:
Mexico--History--1867-1910.
Mexico--History--Revolution, 1910-1920.
Mineral industries--Mexico--History.
Mines and mineral resources--Mexico--History.