Columbia subject headings:
Energy policy--United States.
Natural gas--Prices--United States.
Petroleum as fuel--Prices--United States.
Harvard subject headings:
Energy policy--United States
Natural gas--Prices--United States
Petroleum as fuel--Prices--United States.
Princeton subject headings:
Energy policy--United States.
Natural gas--Prices--United States.
Petroleum as fuel--Prices--United States.