Bijan Davvaz
Department of Mathematics, Yazd University, Yazd, Iran
Madad Khan
Department of Mathematics, COMSATS Institute of Information Technology, Abbottabad, Pakistan
Kifayat Ullah
Department of Mathematics, COMSATS Institute of Information Technology, Abbottabad, Pakistan
Usman Ashraf
Department of Mathematics, COMSATS Institute of Information Technology, Abbottabad, Pakistan