Columbia subject headings:
Developing countries--Prospecting--Congresses.
Petroleum--Developing countries--Congresses.
Harvard subject headings:
Petroleum--Developing countries--Congresses.
Petroleum--Prospecting--Developing countries--Congresses.
Prospecting--Developing countries--Congresses.
Princeton subject headings:
Petroleum industry and trade--Congresses.
Petroleum industry and trade--Developing countries--Congresses.