Columbia subject headings:
Harvard subject headings:
Agricultural ecology--Research--France--History.
Agricultural ecology--Sahel--International cooperation.
Agricultural engineering--Research--France--History.
Agricultural engineering--Sahel--International cooperation.
Agricultural engineers--France--Biography.
Arid regions agriculture--Sahel.
Billaz, R.
Princeton subject headings:
Agricultural ecology--Sahel.
Agriculture--Economic aspects--Sahel.
Sustainable agriculture--Sahel.