Columbia subject headings:
Petroleum industry and trade--United States--History.
Petroleum industry and trade--Venezuela--History.
United States--Foreign economic relations--Venezuela.
Venezuela--Foreign economic relations--United States.
Harvard subject headings:
Petroleum industry and trade--United States--History
Petroleum industry and trade--Venezuela--History
United States--Foreign economic relations--Venezuela.
Venezuela--Foreign economic relations--United States.
Princeton subject headings:
Petroleum industry and trade--United States--History.
Petroleum industry and trade--Venezuela--History.
United States--Foreign economic relations--Venezuela.
Venezuela--Foreign economic relations--United States.