Columbia subject headings:
Labor unions--Mexico--History--Periodicals.
Working class--Mexico--History--Periodicals.
Harvard subject headings:
Labor unions--Mexico--History--Periodicals.
Labor--Mexico--History--Periodicals.
Working class--Mexico--History--Periodicals.
Princeton subject headings:
Labor movement--Mexico--History--Periodicals.
Labor unions--Mexico--History--Periodicals.
Working class--Mexico--History--Periodicals.