4Arthue J. External Trade in Developing Economies [J]. NBER, WorkingPaper,2001 (11).
5PortorMichael E. Competitive Strategy[M]. New York: The Free Press, 1999.
6Ellison, G. Glaser L. E and Kerr, W. What Causes Industry Agglomeration? Evidence from Concentration Pattern [C ]. NBER Working Paper No. 13068, 2007, 5-12.