Columbia subject headings:
Air--Pollution--Environmental aspects.
Global warming.
Greenhouse effect, Atmospheric.
Motor vehicles--Motors--Exhaust gas.
Harvard subject headings:
Air quality management
Air--Pollution--Environmental aspects.
Energy policy--United States
Global warming
Greenhouse effect, Atmospheric
Motor vehicles--Environmental aspects.
Motor vehicles--Motors--Exhaust gas--Environmental aspects--United States.
Motor vehicles--Motors--Exhaust gas--Environmental aspects.
Transportation and state--United States.
Princeton subject headings:
Energy policy--United States.
Global warming.
Motor vehicles--Motors--Exhaust gas--Environmental aspects--United States.
Transportation and state--United States.