1、The Effect of NAFTA on Energy and Environmental Efficiency in Mexico ，  Authors: David I. Stern， Policy Studies Journal, Volume 35, Issue  2,May 2007 , pages 291 - 322


2、Fostering Environment-Efficiency Through Transnational Linkages? Trajectories of CO2 and SO2, 1980-2000  ，  Authors: Richard Perkins，Eric Neumayer，Environment and Planning A, Vol. 40, No. 12, 2008



3、On the environmental efficiency of economic systems  ，  Authors: Robert J. McIntyre; James R. Thornton，  [url=./title~db=all~content=t713414944]Europe-Asia StudiesVolume 30, Issue2 , April 1978 , pages 173 - 192