Columbia subject headings:
Petroleum industry and trade--Government policy--United States--History--20th century.
Petroleum industry and trade--Political aspects--United States.
United States--Foreign relations--20th century.
Harvard subject headings:
Petroleum industry and trade--Government policy--United States--History--20th century.
Petroleum industry and trade--Political aspects--United States
United States--Foreign relations--20th century.
Princeton subject headings:
Petroleum industry and trade--Government policy--United States--History--20th century.
Petroleum industry and trade--Political aspects--United States.
United States--Foreign relations--20th century.