1. Department of Otorhinolaryngology, Faculty of Medicine of the Military Medical Academy University of Defence Belgrade Serbia
2. ENT Department Lovisenberg Diakonale Hospital Oslo Norway
3. Clinical Center of Serbia, Clinic for Infectious and Tropical Diseases, School of Medicine University in Belgrade Belgrade Serbia
4. Department of Otorhinolaryngology Clinical Center of Montenegro Podgorica Montenegro
5. Clinical Center of Serbia, Clinic for Otorhinolaryngology and Maxillofacial Surgery, School of Medicine University in Belgrade Belgrade Serbia
6. Institute for Medical Research, Division of Clinical and Experimental Immunology, Military Medical Academy Faculty of Medicine University of Defence Belgrade Serbia