8Subrahmanya M H B. Labour productivity,energy intensity and economic performance in small enterprises :a study o:f brick enterprises cluster in india[J]. Energy Conversion and Management, 2006, 47(6): 763777.
9Folta T B, Cooper A C, Baik Y. Geographic cluster size and firm performance[J]. Journal of Business Venturing, 2006, 21(2): 217-242.
10Gilbert B A, Mcdougall P P, Auretsch D B. Clusters, knowledge spillovers and new venture performance:an empirical e xamination[J]. Journal of Business Venturing,2008,23(4) : 405-422.
