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Journal of Productivity Analysis > 2010 > 33 > 3 > 209-223
Frontiers of Economics in China > 2007 > 2 > 2 > 212-223
Journal of Productivity Analysis > 2010 > 33 > 3 > 209-223
Frontiers of Economics in China > 2007 > 2 > 2 > 212-223