[1] Hazara Univ Mansehra, Dept Phys, Mansehra, Pakistan
[2] Majmaah Univ, Coll Sci Al Zulfi, Dept Math, POB 66, Al Majmaah 11952, Saudi Arabia
[3] Abbottabad Univ Sci & Technol, Dept Math, Abbottabad, Pakistan
[4] Beijing Inst Technol, Sch Math & Stat, Beijing 100081, Peoples R China
[5] Hazara Univ Mansehra, Dept Math & Stat, Mansehra, Kpk, Pakistan