Columbia subject headings:
Agricultural ecology--United States.
Agricultural systems--United States--Case studies.
Agricultural systems--United States.
Agriculture and state--United States.
Agriculture--Economic aspects--United States.
Harvard subject headings:
Agricultural systems--United States--Case studies.
Alternative agriculture--United States.
Princeton subject headings:
Agricultural ecology--United States.
Agricultural systems--United States.
Agriculture and state--United States.
Agriculture--Economic aspects--United States.