1. Department of Technology and Management, Faculty of Technology Management and Business, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor, Malaysia
2. School of Mathematical Sciences, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
3. Department of Mathematics, Madras Christian College, Tambaram, Chennai 600059 India