Columbia subject headings:
Harvard subject headings:
Energy policy--Canada--History--20th century.
Gas industry--Government policy--Canada--History--20th century.
Petroleum industry and trade--Government policy--Canada--History--20th century.
Princeton subject headings:
Energy policy--Canada--History--20th century.
Gas industry--Government policy--Canada--History--20th century.
Petroleum industry and trade--Government policy--Canada--History--20th century.