Columbia subject headings:
Election law--Mexico--History--20th century.
Elections--Mexico--History--20th century.
Partido Revolucionario Institucional--History--20th century.
Harvard subject headings:
Election law--Mexico--History--20th century.
Elections--Mexico--History--20th century.
Partido Revolucionario Institucional--History--20th century.
Princeton subject headings:
Election law--Mexico--History--20th century.
Elections--Mexico--History--20th century.
Partido Revolucionario Institucional--History--20th century.