Columbia subject headings:
Harvard subject headings:
Labor unions--Latin America--History--Chronology.
Labor unions--Latin America--History.
Socialism--Latin America--Chronology.
Socialism--Latin America--History--Chronology.
Socialism--Latin America--History.
Working class--Latin America--History.
Working class--Political activity--Latin America--History--Chronology.
Princeton subject headings:
Labor movement--Latin America--History--Chronology.
Socialism--Latin America--History--Chronology.