[Chen, De-Han] Cent China Normal Univ, Sch Math & Stat, Wuhan 430079, Peoples R China.
[Chen, De-Han] Cent China Normal Univ, Hubei Key Lab Math Sci, Wuhan 430079, Peoples R China.
[Li, Jingzhi] Southern Univ Sci & Technol, Dept Math, Shenzhen 518055, Peoples R China.
[Li, Jingzhi] Southern Univ Sci & Technol, Natl Ctr Appl Math Shenzhen, Shenzhen 518055, Peoples R China.
[Li, Jingzhi] Southern Univ Sci & Technol, SUSTech Int Ctr Math, Shenzhen 518055, Peoples R China.