1. School of Mathematics and Statistics, Northwestern Polytechnical University, Xi'an 710072, Shannxi, China
2. Department of Mathematics, College of Science, Sana'a University, Sana'a, Yemen
3. Department of Mathematics, College of Science, China University of Geoscience, Wuhan, China
4. Mathematics Department, Faculty of Science and Technology, Suan Dusit University, Bangkok 10300, Thailand
5. Department of Mathematics, Shaheed Benazir Bhutto University, Sheringal, Dir Upper 18000, Khyber Pakhtunkhwa, Pakistan
6. Department of Mathematics, Azarbaijan Shahid Madani University, Tabriz, Iran
7. Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan