Columbia subject headings:
Grain trade--England--London--History--18th century.
Grain trade--France--Paris--History--18th century.
Harvard subject headings:
Grain trade--England--London--History--18th century.
Grain trade--France--Paris--History--18th century.
Princeton subject headings:
Grain trade--England--London--History--18th century.
Grain trade--France--Paris--History--18th century.