[Shen, Jian-Mei] Hunan Univ, Sch Finance & Stat, Changsha 410079, Peoples R China.
[Rashid, Saima] Govt Coll Univ, Dept Math, Faisalabad 38000, Pakistan.
[Noor, Muhammad Aslam] COMSATS Univ Islamabad, Dept Math, Islamabad 44000, Pakistan.
[Ashraf, Rehana] Lahore Coll Women Univ, Dept Math, Lahore 54660, Pakistan.
[Chu, Yu-Ming] Huzhou Univ, Dept Math, Huzhou 313000, Peoples R China.