1. Department of Mathematics, College of Science, University of Al-Qadisiyah, Al Diwaniyah 58001, Al-Qadisiyah, Iraq
2. Department of Mathematics, “1 Decembrie 1918” University of Alba-Iulia, 510009 Alba-Iulia, Romania
3. Department of Mathematics, Technical University of Cluj-Napoca, 400114 Cluj-Napoca, Romania