Columbia subject headings:
Harvard subject headings:
East-West trade.
Gas industry--Political aspects--Europe.
Gas industry--Political aspects--Soviet Union.
Natural gas pipelines--Europe.
Natural gas pipelines--Soviet Union.
Princeton subject headings:
East-West trade.
Gas industry--Political aspects--Europe.
Gas industry--Political aspects--Soviet Union.
Natural gas pipelines--Europe.
Natural gas pipelines--Soviet Union.