Columbia subject headings:
Air--Pollution--Standards--United States.
Coal-fired power plants--United States.
United States. Environmental Protection Agency.
Harvard subject headings:
Air--Pollution--Standards--United States
Coal-fired power plants--United States.
United States. Environmental Protection Agency
Princeton subject headings:
Air--Pollution--Standards--United States.
Coal-fired power plants--United States.
United States. Environmental Protection Agency