1. Department of Mathematics, Abdul Wali Khan University, Mardan Khyber Pakhtunkhwa, Pakistan
2. Section of Mathematics, International Telematic University Uninettuno, Corso Vittorio, Emanuele II, 39, 00186 Roma, Italy
3. Department of Mathematics, COMSATS University, Islamabad, Attock Campus Punjab, Pakistan
4. Department of Physics, College of Science, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia