1. Faculty of Mechanics and Mathematics, National University of Uzbekistan, Vuzgorodok, Tashkent, Uzbekistan
2. Department of Mathematical Sciences, College of Science, The United Arab Emirates University, Al Ain, Abu Dhabi, UAE
3. Department of Mathematics, The Abdus Salam International Centre for Theoretical Sciences, Trieste, Italy
4. Faculty of Science, Department of Mathematics, Tafila Technical University, Tafila, Jordan