Columbia subject headings:
Natural gas--Geology--West (U.S.)
Petroleum--Geology--West (U.S.)
Harvard subject headings:
Geology, Stratigraphic.
Hydrocarbons.
Petroleum--Geology--Rocky Mountains Region.
Petrology--Rocky Mountains Region.
Princeton subject headings:
Natural gas--Geology--West (U.S.)--Congresses.
Petroleum--Geology--West (U.S.)--Congresses.