Columbia subject headings:
Agriculture--Early works to 1800.
Crops--Early works to 1800.
Crops--Economic aspects--Early works to 1800.
Traditional medicine--Early works to 1800.
Harvard subject headings:
Agriculture--Early works to 1800
Agriculture.
Crops--Early works to 1800.
Crops--Economic aspects--Early works to 1800.
Traditional medicine--Early works to 1800.
Princeton subject headings: