1. State University of Novi Pazar, Vuka Karadzica bb, 36300 Novi Pazar, Serbia
2. Department of Mechanics, Faculty of Technical Sciences, University of Novi Sad, Trg D. Obradovica 6, 21000 Novi Sad, Serbia
3. College of Engineering and Science, Victoria University, Footscray Park Campus, Melbourne, Victoria, Australia
4. Mathematical Institute, Serbian Academy of Arts and Sciences, Kneza Mihaila 36, 11000 Belgrade, Serbia