5Christian K. The development of the cluster concept-present experiences and further developments. [2010 -03 - 16 ]. http://estrategiadelisboa, org/doeument/development_cluster_concept, pdf.
6Surinach J, Moreno R, Vaya E. Knowledge externalities, innovation clusters and regional development. Cornwall: Edward Elgar Publishing Limited Glensanda House ,2007:2 - 18.
7Ahuja G. Collaboration networks, structural holes, and innovation : A longitudinal study. Administrative Science Quarterly, 2000,45 (3) :425 -455.
8Salman N, Salves A L. Indirect networks: An intangible resource for biotechnology innovation. R&D Management, 2005,35 ( 2 ) : 203 -215.
9Lorenzen M. Breakout from bollywood? The roles of social networks and regulation in the evolution of Indian film industry. Journal of International Management, 2008,14 ( 3 ) : 286 - 299.
10Krackhardt D, Kilduff M. Friendship patterns and culture: The control of organizational diversity. American Anthropologist, 1990, 92(1) : 142 -154.
