T. Mansour

Department of Mathematics, University of Haifa, 3498838 Haifa, Israel

M. A. Rostami

Institute for Computer Science, Friedrich Schiller University Jena, Germany

E. Suresh

Department of Mathematics, Velammal Engineering College, Surapet, Chennai-66, Tamil Nadu, India

G. B. A. Xavier

Department of Mathematics, Sacred Heart College, Tirupattur-635601, Tamil Nadu, India