1. Hohai University, College of Engineering Mechanics and Materials, Nanjing, P. R. China + Çankaya University, Department of Mathematics, Ankara, Turkey + Institute of Space Sciences, Magurele-Bucharest, Romania
2. University of Thi-Qar, Faculty of Education for Pure Sciences, Department of Mathematics, Nasiriyah, Iraq
3. Shaheed BB University, Department of Mathematics, Sheringal, Dir Upper, Khyber Pakhtunkhwa, Pakistan