Columbia subject headings:
Agricultural geography--Korea--Early works to 1800.
Agriculture--Korea--Early works to 1800.
Field crops--Korea--Early works to 1800.
Harvard subject headings:
Agricultural geography--Korea--Early works to 1800.
Agriculture--Korea--Early works to 1800.
Field crops--Korea--Early works to 1800.
Princeton subject headings:
Agriculture and state--Korea--Early works to 1800.
Agriculture--Korea--History--Early works to 1800.