1. Department of Applied Mathematics, Faculty of Mathematical Sciences, Ferdowsi University of Mashhad, Mashhad, Iran
2. Department of Mathematical Sciences, Faculty of Engineering and Science, University of Agder, Kristiansand, Norway
3. Department of Language, Literature, Mathematics, and Interpreting, Faculty of Teacher Education, Culture, and Sport, Western Norway University of Applied Sciences, Bergen, Norway
4. School of Education, Faculty of Education, Victoria University of Wellington, Wellington, New Zealand