6David,Paul A., 1969,A Contribution to the Theory of Diffusion[R].Stanford University: Center for Research in Economic Growth Research Memorandum No.71.1975, The Mechanization of Reaping in the Ante-bellumMidwest[J].Technical Choice, Innovation, and Economic Growth.Cambridge University Press, 195-232.
7Kamien, M.I., N.L.Schwarz.Market structure and innovation:A survey[J]. Journal of Economic Literature, 1975, ( 13 ) : 1-37.
8Mansfield, E.How rap dly does new industrial technology leak out? [J]. Journal of Industrial Economics, 1985, (34) : 217-223.
9Dasgatpta, Partha & Stiglitz, Joseph.Uncertainty, Industrial Structure, and the Speed of R&D[J].Bell Journal of Economics ,The RAND Corporation, 1980,11 ( 1 ) : 1-28.
10Harris, Christopher J & Vickers.John S.Patent Races and the Persistence of Monopoly[J].Journal of Industrial Economics, Blackwell Publishing, 1985,33 (4) :461-81.
