[1] Southwestern Univ Finance & Econ, Sch Business Adm, Fac Business Adm, Chengdu 610074, Sichuan, Peoples R China
[2] Southwestern Univ Finance & Econ, Sch Econ Math, Chengdu 610074, Sichuan, Peoples R China
[3] Wilfrid Laurier Univ, Dept Math, Waterloo, ON N2L 3C5, Canada
[4] Shanghai Customs Coll, Grad Sch, Shanghai 201201, Peoples R China