1. Dongeui University, Department of Mathematics, Busan, Korea
2. National and Capodistrian University of Athens, Pedagogical Department E.E., Section of Mathematics and Informatics, Aghia Paraskevi, Athens, Greece
3. King Abdulaziz University, Department of Mathematics, Jeddah, Saudi Arabia
4. Gyeongsang National University, Department of Mathematics Education and the RINS, Jinju, Korea + King Abdulaziz University, Department of Mathematics, Jeddah, Saudi Arabia