8Barro R J, Sala-i-Martin X. Convergence[ J]. Journal of Political Economy, 1992, 100(2) :223 -251.
9Mankiw N G. , Romer D, Weil-D. A Contribution to the Empirics of Economic Growth [ J]. Quarterly Journal. of Economics, 1992, 107:34 - 79.
10Arellano, Bond S. Some Tests of Specification for Panel Data: Monte Carlo Evidence and an Application to Employment Equations [ J ]. Review of Economic Studies, 1991, 58 : 277 - 297.
