1. School of Mathematics and Statistics, Southwest University, Chongqing, China.
2. Department of Mathematics, Aligarh Muslim University, Aligarh, India.
3. Department of Mathematics and Statistics, King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia.
4. Center for General Education, China Medical University, Taichung, Taiwan.
5. Department of Mathematics, King Abdulaziz University, Jeddah, Saudi Arabia.