Author/Authors :
Mortazavizadeh, M Department of Mathematics - Ferdowsi University of Mashhad, Mashhad, Islamic Republic of Iran , Raisi Tousi, R Department of Mathematics - Ferdowsi University of Mashhad, Mashhad, Islamic Republic of Iran , Kamyabi Gol, R.A Department of Mathematics - Ferdowsi University of Mashhad, Mashhad, Islamic Republic of Iran