1. School of Medicine, Josip Juraj Strossmayer University of Osijek; Department of Neurosurgery; Josipa Huttlera 4 Osijek Croatia 31 000
2. Josip Juraj Strossmayer University of Osijek; Department of Methodological and Informatical Sciences, Faculty of Law; Stjepana Radiaea 13 Osijek Croatia HR-31 000
3. Gentofte University Hospital of Copenhagen; Department of Otorhinolaryngology Head and Neck Surgery; Hellerup Denmark DK-2900