7Bai C,Du Y,Tao Z,et al. Local Protectionism and Re gional Spreialization.. Evidence from China ' s Industries [J]. Journal of International Economics, 2004,63 ( 2 ) : 397-418.
8Lu Y, Tao Z. Trends and Determinants of China's In- dustrial Agglomeration [J]. Journal of Urban Econom- ics, 2009,65 : 267- 180.
9Krugman P. Increasing Returns and Economic Geogra phy[J]. Journal of Political Economy, 1991,99. 483- 499.