M. Rashad
Department of Mathematics, University of Malakand, Chakdara Dir L, Pakistan
I. Ahmad
Department of Mathematics, University of Malakand, Chakdara Dir L, Pakistan
M. Shah
Department of Mathematics, University of Malakand, Chakdara Dir L, Pakistan
Z. U. A. Khuhro
Department of Mathematics, University of Malakand, Chakdara Dir L, Pakistan