Columbia subject headings:
Maps.
Natural gas--North America--Maps.
Oil-shales--North America--Maps.
Harvard subject headings:
Gas fields--North America--Maps.
Gas industry--North America--Maps.
Liquefied natural gas industry--North America--Maps.
Liquefied natural gas shipping terminals--North America--Maps.
Natural gas pipelines--North America--Maps.
Natural gas--North America--Maps.
Oil-shales--North America--Maps.
Thematic maps.
Princeton subject headings:
Gas fields--Maps.
Gas industry--Maps.
Liquefied natural gas industry--Maps.
Liquefied natural gas shipping terminals--Maps.
Maps.
Natural gas pipelines--Maps.
Natural gas--Maps.
North America--Maps.
Shale gas reservoirs--North America--Maps.
Shale--North America--Maps.
Thematic maps.