Author/Authors :
R. Saadati، R. Saadati نويسنده Faculty of Sciences, University of Shomal, Amol, P.O. Box 731, Iran , , S. Sedghi، S. Sedghi نويسنده Department of Mathematics, Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran S. Sedghi, S. Sedghi , H. Zhou، H. Zhou نويسنده Department of Mathematics, Shijiazhuang Mechnical Engineering University, Shijiazhuang 050003, People’s Republic of China ,
