Columbia subject headings:
Harvard subject headings:
Competition, International--History--19th century.
Competition, International--History--20th century.
Petroleum industry and trade--History--19th century.
Petroleum industry and trade--History--20th century.
Princeton subject headings:
Competition, International--History--19th century.
Competition, International--History--20th century.
Petroleum industry and trade--History--19th century.
Petroleum industry and trade--History--20th century.