1. School of Mathematics and Physics, Anhui Jianzhu University, Hefei230601, China
2. Department of Mathematics and Statistics, The University of Lahore, Lahore54000, Pakistan
3. Department of Mathematics, COMSATS University Islamabad, Lahore Campus, LahorePakistan
4. Department of Basic Science and Humanities, University of Engineering and Technology, Lahore (Narowal Campus), LahorePakistan