Columbia subject headings:
Harvard subject headings:
Natural gas in submerged lands--North Sea--Congresses.
Offshore oil well drilling--North Sea--Congresses.
Petroleum in submerged lands--North Sea--Congresses.
Petroleum--Geology--North Sea--Congresses.
Princeton subject headings:
Geology--North Sea--Congresses.
Natural gas in submerged lands--North Sea--Congresses.
Petroleum--Geology--North Sea--Congresses.