Columbia subject headings:
Labor movement--Mexico--History--20th century.
Lombardo Toledano, Vicente, 1894-1968.
Working class--Mexico--History--20th century.
Harvard subject headings:
International labor activities--History--20th century.
Labor unions--Mexico--History--20th century.
Labor unions--United States--History--20th century
Lombardo Toledano, Vicente, 1894-1968
Princeton subject headings:
Labor movement--Mexico--History--20th century.
Lombardo Toledano, Vicente, 1894-1968.
Working class--Mexico--History--20th century.