Columbia subject headings:
Maps.
Natural gas--Former Soviet republics--Maps.
Petroleum--Former Soviet republics--Maps.
Pipelines--Former Soviet republics--Maps.
Harvard subject headings:
Gas fields--Former Soviet republics--Maps.
Natural gas--Former Soviet republics--Maps.
Oil fields--Former Soviet republics--Maps.
Petroleum--Former Soviet republics--Maps.
Pipelines--Former Soviet republics--Maps.
Power resources--Former Soviet republics--Maps.
Princeton subject headings: