[Song, Ying-Qing] Hunan City Univ, Coll Sci, Yiyang 413000, Peoples R China.
[Waqas, Hassan; Khan, Shan Ali] Univ Faisalabad, Govt Coll, Dept Math, Layyah Campus, Faisalabad 31200, Pakistan.
[Khan, Sami Ullah] COMSATS Univ Islamabad, Dept Math, Sahiwal 57000, Pakistan.
[Khan, M. Ijaz] Riphah Int Univ I 14, Dept Math & Stat, Islamabad 44000, Pakistan.
[Chu, Yu-Ming] Huzhou Univ, Dept Math, Huzhou 313000, Peoples R China.