Columbia subject headings:
Agriculture--Periodicals.
Agriculture--United States--Periodicals.
United States. Department of Agriculture--Periodicals.
Harvard subject headings:
Agriculture--Periodicals
Agriculture--United States--Periodicals
United States. Department of Agriculture--Periodicals.
Princeton subject headings:
Agriculture--Periodicals.
Agriculture--United States--Periodicals.
Periodicals.
United States. Department of Agriculture--Periodicals.