1. Faculty of Electrical Engineering and Information Technologies Ss. Cyril and Methodius University of Skopje Rugjer Boshkovikj 1000 Skopje North Macedonia
2. Department of Physics and Mathematics University of Eastern Finland P.O. Box 111 FI‐80101 Joensuu Finland
3. Faculty of Mathematics University of Vienna Oskar Morgenstern Platz 1 1090 Wien Austria