Columbia subject headings:
Harvard subject headings:
Food supply--Senegal River Valley.
Labor productivity--Senegal River Valley.
Rice trade--Senegal River Valley.
Rice--Prices--Senegal River Valley.
Princeton subject headings:
Food supply--Senegal River Valley.
Labor productivity--Senegal River Valley.
Rice trade--Senegal River Valley.
Rice--Prices--Senegal River Valley.
Rice--Senegal River Valley--Marketing.