Ow does the emergence of recently prominent economically and politically powerful states alter conceptions of core and periphery?

Please try and use quotes from:

Lees, N. (2012). i??The dimensions of the divide: Vertical differentiation, international inequality and North-South stratification in international relations theoryi??. Cambridge review of international affairs 25:2, pp. 209-230

Lustick, I. (1997). i??The absence of Middle Eastern great powers: Political i??backwardnessi?? in historical perspectivei??. International organization 51:4, pp. 653-683

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If you cant find them, contact me please

Added on 08.01.2015 12:12
I have attached the following papers, so please use relevant quotes from these sources !