Columbia subject headings:
Harvard subject headings:
Agriculture--Economic aspects--Europe--History--18th century--Congresses.
Agriculture--Economic aspects--Europe--History--19th century--Congresses.
Agriculture--Environmental aspects--Europe--History--18th century--Congresses.
Agriculture--Europe--History--18th century--Congresses.
Economics--Europe--Societies, etc.--History--18th century--Congresses.
Natural resources--Europe--History--18th century--Congresses.
Princeton subject headings:
Agriculture--Economic aspects--Europe--History--19th century--Congresses.
Agriculture--Europe--History--18th century--Congresses.
Economics--Europe--Societies, etc.--History--19th century--Congresses.