1. Department of Mathematics , Government College University , Faisalabad , Pakistan
2. Department of Mathematics , Huzhou University , Huzhou , China ; Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering , Chengsha University of Science and Tehnology , Changsha , China
3. Department of Mathematics, School of Natural Sciences , National University of Sciences and Technology , H-12 , Islamabad , Pakistan
4. Department of Mathematics , Riphah Institute of Computing and Applied Sciences Riphah International University , Lahore , Pakistan