Columbia subject headings:
Energy industries--Developing countries.
Energy industries.
Petroleum industry and trade--Developing countries.
Petroleum industry and trade.
Harvard subject headings:
Energy industries
Energy industries--Developing countries.
Petroleum industry and trade--Developing countries
Petroleum industry and trade.
Princeton subject headings:
Energy industries--Developing countries.
Energy industries.
Petroleum industry and trade--Developing countries.
Petroleum industry and trade.