Columbia subject headings:
Harbors--Mexico--Salina Cruz.
Petroleum industry and trade--Mexico--Salina Cruz.
Tehuantepec, Isthmus of (Mexico)--Economic conditions.
Harvard subject headings:
Harbors--Mexico--Salina Cruz.
Petroleum industry and trade--Mexico--Salina Cruz.
Tehuantepec, Isthmus of (Mexico)--Economic conditions.
Princeton subject headings:
Harbors--Mexico--Salina Cruz.
Petroleum industry and trade--Mexico--Salina Cruz.
Tehuantepec, Isthmus of (Mexico)--Economic conditions.