Columbia subject headings:
Acid deposition--Environmental aspects.
Acid precipitation (Meteorology)--Environmental aspects.
Forest ecology.
Plants--Effect of acid precipitation on.
Harvard subject headings:
Acid deposition--Environmental aspects--Congresses.
Acid precipitation (Meteorology)--Environmental aspects--Congresses.
Forest ecology--Congresses
Plants--Effect of acid precipitation on--Congresses.
Princeton subject headings: