[Song, Ying-Qing] Hunan City Univ, Coll Sci, Yiyang 413000, Peoples R China.
[Khan, Sami Ullah] COMSATS Univ Islamabad, Dept Math, Sahiwal 57000, Pakistan.
[Khan, M. Ijaz] Riphah Int Univ, Dept Math, I-14 Islamabad 44000, Pakistan.
[Khan, M. Ijaz] King Abdulaziz Univ, Dept Math, Nonlinear Anal & Appl Math NAAM Res Grp, Fac Sci, P Box 80257, Jeddah 21589, Saudi Arabia.
[Awais, Muhammad] PMAS Arid Agr Univ, Univ Inst Biochem & Biotechnol, Rawalpindi, Pakistan.