1. Department of Physics, Mimar Sinan Fine Arts University, Bomonti 34380, Istanbul, Turkey
2. Department of Mathematics, Khazar University, Mehseti St. 41, AZ1096, Baku, Azerbaijan
3. Institute of Radiation Problems ANAS, B.Vahabzade 9, AZ1143 Baku, Azerbaijan
4. Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, D-14476 Potsdam, Germany