OU Bian-ling
School of Economy and Trade , South China University of Technology , Guangzhou 510640 , China;LONG Zhi-he
School of Economy and Trade , South China University of Technology , Guangzhou 510640 , China; Academy of Mathematics and Systems Science , Chinese Academy of Sciences , Beijing 100190 , China ;LIN Kuang-ping
Department of Economics , Portland State University , Portland , Oregon , 97207 , USA )