Columbia subject headings:
Harvard subject headings:
Chile saltpeter industry--Chile--Employees--History--19th century.
Chile saltpeter industry--Chile--Employees--History--20th century.
Chile saltpeter industry--Social aspects--Chile.
Chile--Politics and government--1824-1920.
Chile--Social conditions.
Working class--Chile--History--19th century.
Working class--Chile--History--20th century.
Princeton subject headings:
Chile saltpeter industry--Chile--Employees--History--19th century.
Chile saltpeter industry--Chile--Employees--History--20th century.
Chile saltpeter industry--Social aspects--Chile.
Chile--Politics and government--1824-1920.
Chile--Social conditions.
Working class--Chile--History--19th century.
Working class--Chile--History--20th century.