1. Faculty of Sciences and Mathematics, University of Niš, 18000 Niš, Serbia
2. Department of Mathematics, State University of Novi Pazar, 36300 Novi Pazar, Serbia
3. Faculty of Mathematics, National University of Uzbekistan Named after Mirzo Ulugbek, Str. University 4, Tashkent 100174, Uzbekistan
4. Department of Exact Sciences, Yeoju Technical Institute in Tashkent, Str. Usman Nasyr 156, Tashkent 100121, Uzbekistan