1. School of Mathematical SciencesDalian University of Technology Dalian China
2. Department of MathematicsCOMSATS University Islamabad, Attock Campus Attock Pakistan
3. Department of MathematicsCOMSATS University Islamabad, Wah Campus Rawalpindi Pakistan
4. Department of Mathematics and StatisticsKing Fahad University of Petroleum and Minerals Dhahran Saudi Arabia