Columbia subject headings:
Commuting--Mexico--Mexico City Metropolitan Area.
Labor supply--Mexico--Mexico City Metropolitan Area.
Subways--Mexico--Mexico City Metropolitan Area.
Transportation--Mexico--Mexico City Metropolitan Area.
Harvard subject headings:
Commuting--Mexico--Mexico City Metropolitan Area.
Labor supply--Mexico--Mexico City Metropolitan Area.
Subways--Mexico--Mexico City Metropolitan Area.
Transportation--Mexico--Mexico City Metropolitan Area.
Princeton subject headings:
Local transit--Mexico--Mexico City.
Transportation--Mexico--Mexico City.
Transportation--Social aspects--Mexico--Mexico City.
Working class--Mexico--Mexico City--Transportation.