1. Faculty of Electronic Engineering, University of Nis, Nis, Serbia
2. Institute of Technical Sciences, Serbian Academy of Sciences and Arts, University of Belgrade, Belgrade, Serbia
3. Faculty of Mechanical Engineering, University of Belgrade, Belgrade, Serbia
4. Faculty of Teachers Education, University of K. Mitrovica, Leposavic, Serbia
5. Faculty of Science, University of Nis, Nis, Serbia
6. Institute of Functional Nanosystems, University of Ulm, Ulm, Germany
7. North Carolina Central University (NCCU), Durham, NC, USA