1. Department of Mathematical Sciences, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia
2. Department of Mathematics and Computer Science, Faculty of Natural and Applied Sciences, Sule Lamido University Kafin Hausa 048, Jigawa State, Nigeria
3. Level 23, Menara CIMB, Jalan Stesen Sentral 2, Kuala Lumpur Sentral, 50470 Kuala Lumpur, Malaysia