2W.H.Wischmeier.Predicting rainfall-erosion losses from cropland east of the Rocky Mountains.Handbook Department of Agriculture Washington D.C.1965.
3Renard,K.G.,Foster,G.R.,Weesies,G.A.,McCool,D.K.,Yoder,D.C.Predicting soil erosion by water;a guide to conservation planning with the revised universal soil loss equation.Handbook Department of Agriculture Washington D.C.1997,703.