1Robert Hamwey,Ulrich Hoffmann,Alexey Vikhlyaev,Rene Vosssenaar. Liberalization of international trade in environmental goods and services[M].Trade,Environment and Development Branch,Division on International Trade in Goods and Services,and Com modities UNCTAD secretariat,2003.
2Ron Wyden. International Trade in Environmental Goods,2012 Report[R].2012.