Columbia subject headings:
Harvard subject headings:
East-West trade.
Europe--Commerce--Soviet Union.
Natural gas pipelines.
Soviet Union--Commerce--Europe.
United States--Commercial policy.
Princeton subject headings:
Europe--Foreign relations--Soviet Union.
Europe--Foreign relations--United States.
Gas industry--Political aspects--Europe.
Gas industry--Political aspects--Soviet Union.
Soviet Union--Foreign relations--Europe.
United States--Foreign relations--Europe.