Columbia subject headings:
Acid rain--Environmental aspects--Canada.
Acid rain--Environmental aspects--United States.
Acid rain--Law and legislation--Canada.
Acid rain--Law and legislation--United States.
Harvard subject headings:
Acid rain--Environmental aspects--Canada.
Acid rain--Environmental aspects--United States.
Acid rain--Law and legislation--Canada.
Acid rain--Law and legislation--United States.
Environmental policy--Canada
Environmental policy--United States
Princeton subject headings: