1. Department of Mathematics, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Channai 601103, India
2. Department of Mathematics, UCRD, Chandigarh University, Mohali 140413, India
3. Department of Mathematics, Government Post Graduate College, Rohtak 124001, India
4. Department of Physics and Chemistry, Technical University of Cluj-Napoca, Cluj-Napoca 400641, Romania