लेखक: Abdelkrim Salim

Mouffak Benchohra, Laboratory of Mathematics, Djillali Liabès University of Sidi Bel-Abbès, P.O. Box 89, Sidi Bel-Abbes 22000, Algeria. E-mail: [email protected]/ Phone: +213540230405 Abdelkrim Salim, Laboratory of Mathematics, Djillali Liabès University of Sidi Bel-Abbès, P.O. Box 89, Sidi Bel-Abbes 22000, Algeria. E-mail: [email protected]/ Phone: +213796315208 Yong Zhou, Faculty of Mathematics and Computational Science, Xiangtan University, Hunan 411105, P.R. China. E-mail: [email protected]/ Phone: +0086 732 58292194