Columbia subject headings:
Environmental protection--United States.
Land use--Law and legislation--United States.
Land use--United States.
Nature conservation--United States.
Soil conservation--United States.
Harvard subject headings:
Environmental protection--United States
Land use--Law and legislation--United States
Land use--United States
Nature conservation--United States.
Soil conservation--United States
Princeton subject headings:
Environmental protection--United States.
Land use--Law and legislation--United States.
Land use--United States.
Nature conservation--United States.
Soil conservation--United States.