Columbia subject headings:
Harvard subject headings:
Gas industry--Ontario--Periodicals.
Gas well drilling--Ontario--Periodicals.
Natural gas--Prospecting--Ontario--Periodicals.
Oil well drilling--Ontario--Periodicals.
Petroleum industry and trade--Ontario--Periodicals.
Petroleum--Prospecting--Ontario--Periodicals.
Princeton subject headings:
Petroleum industry and trade--Ontario--Periodieals.