Columbia subject headings:
Environmental policy--United States--Congresses.
Environmental protection--United States--Congresses.
Human ecology--Congresses.
United States--Environmental conditions--Congresses.
Harvard subject headings:
Environmental policy--United States--Congresses
Environmental protection--United States--Congresses
Human ecology--Congresses
United States--Environmental conditions--Congresses.
Princeton subject headings:
Environmental policy--United States--Congresses.
Environmental protection--United States--Congresses.
Human ecology--Congresses.
United States--Environmental conditions--Congresses.