3S Se W.Costand Production Functions Princeton[M].New Jersey:Princeton University Press,1981.
4D G Johnson Fraumene Productivity and US.Economic Gorwth[M].North-Holl and Amsterdam-Oxford,1996.
5S Rozelle.Theory of Costand Production Functions.Princeton[M].New Jersey:Princeton University Press,1998.
6S Holden,B Shiferaw.Land Degradation,Drought and Foods Curityinal Favoure Daream the Ethiopian High Lands:Abio-economic Model with Market Imperfections[J].Agriculture Economics,2008(30):31-49.