1. School of Management Science and Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China
2. Department of Mathematics, Abdul Wali Khan University Mardan, Pakistan
3. Department of Mathematics, Technical University of Cluj-Napoca, Romania
4. Department of Mathematics and Computer Science, Faculty of Informatics and Sciences, University of Oradea, 410087 Oradea, Romania