1. Department of Mathematics, Cankaya University, Ogretmenler Caddesi 14, Balgat, 06530 Ankara, Turkey
2. Institute of Space Sciences, Magurele, Bucharest, Romania
3. Department of Mathematics, Azarbaijan Shahid Madani University, Azarshahr, Tabriz, Iran
4. Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia