Columbia subject headings:
Canals--Mexico.
Indians of Mexico--Agriculture.
Indians of Mexico--Antiquities.
Irrigation farming.
Irrigation--Mexico.
Irrigation.
Mexico--Antiquities.
Harvard subject headings:
Canals--Mexico
Indians of Mexico--Antiquities
Indians of Mexico--Irrigation.
Irrigation--Mexico
Mexico--Antiquities.
Princeton subject headings:
Canals--Mexico.
Indians of Mexico--Antiquities.
Indians of Mexico--Irrigation.
Irrigation--Mexico.
Mexico--Antiquities.