6Maehlup F. The production and distribution of knowledge in the united states [ M 1- New Jersey: Princeton University Press, 1962.
7Dholakia R, Harlam B. Telecommunications and economic development[J]. Telecommunications Policy, 1994(6): 35-38.
8Dewan, Kraemer. Information technology and productivity: evidence from country level data[ Jl. Management Science, 2000, 4(21 ) : 358-363.
9Gust C, Marquez J. International comparisons of productivity growth : the role of information technology and regylatory practics [J]. Labour Economics, 2003, 11 (16) : 33-58.