5Evenson R E.Economic impacts of agricultural research and extension[A] //Gardner B L,Rausser G.Handbook of agricultural economics.New York,NY:North-Holland,2001,1:574-628.
6Mitra S.A nonlinear cobweb model of agricultural commodity price fluctuations,department of economics[J].Fordham University,2008:321-331.
7Van Tongeren,Frank & Van Meijl,Hans & Surry.Yves:Global models applied to agricultural and trade policies:a review and assessment[J].Agricultural Economics,2001,26:157-165.
8Cummings R,Rashid S,Gulati A.Grain price stabilization experiences in Asia:What have we learned[J].Food Policy,2006,31:328-341.
9Shively G E.Food price variability and economic reform:an ARCH approach for ghana[J].American Journal of Agricultural Economics,1996,78:126-136.
10Dana J,Gilbert C,Shim E.Hedging grain price risk in the SADC:case studies of malawi and zambia[J].Food Policy,2006,31:357-371.
