Columbia subject headings:
Labor movement--Mexico.
Labor unions--Mexico--History--20th century.
Working class--Mexico.
Harvard subject headings:
Labor movement--Mexico--History--20th century
Syndicalism--Mexico--History--20th century.
Working class--Mexico--History--20th century.
Princeton subject headings:
Labor movement--Mexico--History--20th century.
Syndicalism--Mexico--History--20th century.
Working class--Mexico--History--20th century.