4Krugman, P.(1991a):Increasing Returns and Economic Georaphy, Journal of Political Economy 99:483-499.
5Krugman, P.(1993a):On thenumber and location of cities,European Economic Review 37:293-298.
6Krugman, P (1998) :Space:The final frontier. Journal of Economic Perspectives 12: 161174.
7Tabuchi, T.(1998):Urbanagglomeration and dispersion,Journal of Urban Economics 44:333 351.
8Fujita, M, (1988): "Amonopolistic competition model of spatial agglomeration: differentiatedproduct approach," Regional Science and Urban Economics 18:87-124.
9Fujita, M. and N. Hamaguchi, 2001: "Intermediate goods andthe spatial structure of an economy,□ Regional Science and Urban Economics 31:79-109.