Columbia subject headings:
Natural gas--Canada.
Natural gas--Government policy--Canada.
Petroleum industry and trade--Canada.
Petroleum industry and trade--Government policy--Canada.
Harvard subject headings:
Natural gas--Canada
Natural gas--Government policy--Canada.
Natural gas--Taxation--Canada.
Petroleum industry and trade--Canada
Petroleum industry and trade--Government policy--Canada.
Petroleum--Taxation--Canada.
Princeton subject headings:
Natural gas--Canada.
Natural gas--Government policy--Canada.
Petroleum industry and trade--Canada.
Petroleum industry and trade--Government policy--Canada.