Affiliation: | 1. Department of Mathematics, Razi University, Kermanshah, Iran.s.jafari.math@gmail.com;3. Department of Mathematics, Razi University, Kermanshah, Iran.;4. Department of Mathematics, Faculty of Science, Arak University, Arak, Iran.;5. Department of Mathematics, International University, Vietnam National University Hochiminh City, Hochiminh City, Vietnam. |