Columbia subject headings:
Harvard subject headings:
Irrigation--Economic aspects--Mexico--Tehuacán River Valley.
Peasants--Mexico--Tehuacán River Valley.
Tehuacán River Valley (Mexico)--Rural conditions.
Princeton subject headings:
Irrigation--Economic aspects--Mexico--Tehuacán River Valley.
Peasants--Mexico--Tehuacán River Valley.
Tehuacán River Valley (Mexico)--Rural conditions.