1. Zain-ul-Abadin Zafar:
Department of Mathematics, University of Engineering and Technology, Lahore, Pakistan
2. M O Ahmad:
Department of Mathematics, University of Engineering and Technology, Lahore, Pakistan
3. A Pervaiz:
Department of Mathematics, University of Engineering and Technology, Lahore, Pakistan
4. Nazir Ahmad:
Department of Mathematics, University of Engineering and Technology, Lahore, Pakistan