1. Department of Mathematics, Garmsar Branch, Islamic Azad University, Garmsar, Iran
2. Department of Mathematics, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia
3. Department of Mathematics, Yadegar-e-Imam Khomeini (RAH), Shahr-e-Rey Branch, Islamic Azad University, Tehran, Iran
4. Department of Mathematics, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran