Columbia subject headings:
Maps.
Natural gas pipelines--North America--Maps.
Natural gas--North America--Maps.
Oil sands--North America--Maps.
Oil-shales--North America--Maps.
Petroleum--North America--Maps.
Harvard subject headings:
Natural gas pipelines--North America--Maps.
Natural gas--North America--Maps.
Oil sands--North America--Maps.
Oil-shales--North America--Maps.
Petroleum--North America--Maps.
Thematic maps.
Princeton subject headings:
Maps.
Natural gas pipelines--North America--Maps.
Natural gas--North America--Maps.
Oil sands--North America--Maps.
Oil-shales--North America--Maps.
Petroleum--North America--Maps.
Thematic maps.