1. Bade F J, Laaser C F, Soltwedel R, 2004. Urban specialization in the internet age: Empirical findings for Germany. Kiel Working Paper, No. 1215.
2. Duranton G, Puga D, 2001. Nursery cities: Urban diversity, process innovation, and the life cycle of products. American Economic Review, 91(5): 1454–1477.
3. Duranton G, Puga D, 2003. Micro-foundations of urban agglomeration economies. Social Science Electronic Publishing, 4(4): 2063–2117.
4. Duranton G, Puga D, 2005. From sectoral to functional urban specialization. Journal of Urban Economics, 57(2): 343–370.
5. Fan Jie, 1993. A study on the industrial structure transformation of coal-mine cities in China. Acta Geographica Sinica, 48(3): 218–225. (in Chinese)