Columbia subject headings:
Gas fields--United States--Maps.
Gas wells--United States--Maps.
Maps.
Natural gas--United States--Maps.
Oil fields--United States--Maps.
Oil wells--United States--Maps.
Petroleum--United States--Maps.
Thematic maps.
United States--Maps.
Harvard subject headings:
Natural gas--United States--Maps.
Petroleum--United States--Maps.
Prospecting--United States--Maps.
Princeton subject headings:
Gas fields.
Maps.
Petroleum.
United States--Maps.