by Gorrie,R.Maclagan.
by Hamilton,C.L.
by Schwab,Glenn O | Barnes,Kenneth K | Frevert,Richard K.
by Frevert,Richard K | Others.
by Soil Conservation Service.
by Dabral,B.G | Qureshi,I.M | Rao,Subba B.K.
by Schwab,G.O | Others.
by FAO.
by Schwab,Glenn O.
by Reij,Chris and others.
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