Columbia subject headings:
Agricultural systems--Congresses.
Agricultural systems--Research--Congresses.
Agriculture--Research--Congresses.
Agriculture--Social aspects--Congresses.
Agriculture--Social aspects--Research--Congresses.
Harvard subject headings:
Agricultural systems--Congresses.
Agricultural systems--Research--Congresses.
Agriculture--Research--Congresses
Agriculture--Social aspects--Congresses.
Agriculture--Social aspects--Research--Congresses.
Princeton subject headings:
Agricultural systems--Congresses.
Agricultural systems--Research--Congresses.
Agriculture--Research--Congresses.
Agriculture--Social aspects--Research--Congresses.
Agriulture--Social aspects--Congresses.