Columbia subject headings:
Hydrocarbons--Secretion--Congresses.
Petroleum--Migration--Congresses.
Petroleum--Prospecting--Congresses.
Schumacher, Dietmar.
Harvard subject headings:
Petroleum--Migration--Congresses.
Princeton subject headings:
Hydrocarbons--Secretion--Congresses.
Petroleum--Migration--Congresses.
Petroleum--Prospecting--Congresses.