1. Department of Mathematics, Izmir University, of Economics, Izmir 35330, Turkey
2. Turgutlu Vocational Training School, Manisa Celal Bayar University, Manisa, Turkey
3. Department of Mathematics, Manisa Celal Bayar University, Manisa 45140, Turkey
4. Department of Mathematics, Muǧla Sıtkı Koçman University, Muǧla, Turkey