Columbia subject headings:
Agriculture--Economic aspects--United States--Congresses.
Commerce--Congresses.
United States--Commerce--Congresses.
United States--Commercial policy--Congresses.
Harvard subject headings:
Agriculture--Economic aspects--United States--Congresses
Commerce--Congresses
United States--Commerce--Congresses.
United States--Commercial policy--Congresses.
Princeton subject headings:
Agriculture--Economic aspects--United States--Congresses.
Commerce--Congresses.
United States--Commerce--Congresses.
United States--Commercial policy--Congresses.