Institution: | 1. Faculty of Sciences, Department of Mathematics, Razi University, Kermanshah, Iran.s.heidarkhani@razi.ac.ir;3. Faculty of Mathematical Sciences, Department of Mathematics, University of Mazandaran, Babolsar, Iran.;4. Department of Mathematics, Baylor University, Waco, TX, USA.;5. Department of Economics, University of Messina, Messina, Italy. |