1. Faculty of Energy Technology, University of Maribor, Hočevarjev trg 1, SI-8270 Krško, Slovenia
2. Faculty of Natural Science and Mathematics, University of Maribor, Koroška Cesta 160, SI-2000 Maribor, Slovenia
3. Center for Applied Mathematics and Theoretical Physics, University of Maribor, Mladinska 3, SI-2000 Maribor, Slovenia
4. Faculty of Civil Engineering, Transportation Engineering and Architecture, University of Maribor, Smetanova 17, SI-2000 Maribor, Slovenia
5. Institute of Mathematics, Physics and Mechanics, Jadranska 19, SI-1000 Ljubljana, Slovenia