1. Department of Economics, Party School of the Beijing Municipal Committee of the Communist Party of China, Beijing, People’s Republic of China
2. School of Environment & Natural Resources, Renmin University of China, Beijing, People’s Republic of China
3. School of Environmental Science & Engineering, Tshinghua University, Beijing, People’s Republic of China
4. School of Energy & Environmental Engineering, Hebei University of Technology, Tianjin, People’s Republic of China