Columbia subject headings:
Labor movement--Mexico--Puebla (State)--20th century--History.
Labor unions--Biography--20th century--Mexico--Puebla (State)--History.
Labor unions--Mexico--Puebla (State)--20th century--History.
Harvard subject headings:
Labor unions--Mexico--Puebla de Zaragoza--History--20th century.
Puebla (Mexico : State)--Social conditions--20th century.
Syndicalism--Mexico--Puebla de Zaragoza--History--20th century.
Princeton subject headings:
Labor unions--Mexico--Puebla de Zaragoza--History--20th century.
Syndicalism--Mexico--Puebla de Zaragoza--History--20th century.