Columbia subject headings:
Petroleum industry and trade--Trinidad and Tobago.
Petroleum industry and trade--Venezuela.
Petroleum--Trinidad and Tobago.
Petroleum--Venezuela.
Petróleo--Industria y comercio--Trinidad (Isla)
Harvard subject headings:
Petroleum industry and trade--Trinidad and Tobago.
Petroleum industry and trade--Venezuela
Petroleum--Trinidad and Tobago.
Petroleum--Venezuela.
Princeton subject headings:
Petroleum industry and trade--Trinidad and Tobago.
Petroleum industry and trade--Venezuela.
Petroleum--Trinidad and Tobago.
Petroleum--Venezuela.