Author(s):
1. Biljana Milutinović, College of Applied Technical Sciences Niš, Serbia
2. Gordana Stefanović, Faculty of Mechanical Engineering in Niš, Serbia
3. Ksenija Denčić-Mihajlov, Ekonomski fakultet Univerziteta u Nišu, Serbia
4. Petar Djekic, The School of Higher Technical Professional Education, Niš, Serbia