4Fulton K. Giannakas. Organizational Commitment in a Mixed Oligopoly:Agricultural Cooperatives and Investor - owned Firms [ J ]. American Journal of Agricultural E- conomics ,2000,83 ( 5 ) : 1258 - 1265.
5Sexton R J. Imperfect Competition in Agricultural Mar- kets and the Role of Cooperatives: A Spatial Analysis [J]. American Journal of Agricultural Economics, 1990, 72(3).
6Tyler B M, Tripathy S. Phytophthora genome sequences uncover evolutionary origins and mechanisms of patho- genesis [ J]. Science,2006,1261 - 1266.
7Douglass C North. Institutional Change and Economic Pero fomance[ M ]. Cambridge University Press, 1990.