1. Department of Mathematics and Statistics, Tshwane University of Technology, Pretoria, South Africa.
2. Operator Theory and Applications Research Group, Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.
3. School of Electronics and Information Engineering, Wuhan Donghu University, Wuhan, P.R. China.
4. Radiation Physics Laboratory, Department of Physics, Faculty of Sciences, Badji Mokhtar University, Annaba, Algeria.
5. Institute of Mathematical Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.
6. Science Program, Texas A & M University at Qatar, Doha, Qatar.