6Stem,L..T. and Common,M.S. Is There an Environmental Kuznets Curve for Sulfur? [J]. Journal of Environmental Economics and Management. 2001,41:162-178.
7Dasgupta,S.,Laplante,B.,Wang, H.,Wheeler,D. Confronting the Envi- ronmental Kuznets Curve [J]. Journal of Economic Perspectives, 2002,16 (1):147-168.