6Bischi, G. , Dawid, H&Kopel, M. Gaining the competitive edge using internal and external spilloVers -a dynamic analysis [J]. Journal of Economic Dynamics & Control, 2003, (27).
7Boschma, R. A. and Frenken, K. Why is economic geography not an evolutionary science? Towards an evolutionary economic geography [J]. Journal of Economic Geography, 2006, (3).
8Boschma, R. and Iammafino, S. Related variety, trade variety and regional growth in Italy [J]. Evolutionary Eco- nomic Geography, 2009, (9).