1. Department of Mathematics, Atilim University, Incek, 06836 Ankara, Turkey
2. Institute of Mathematics, Silesian University of Technology, Gliwice, Poland
3. Department of Mathematics, College of Education of Jubail, Imam Abdulrahman Bin Faisal University, P.O. Box 12020, Jubail 31961, Saudi Arabia
4. Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan