1. University of Novi Sad, Faculty of Medicine, Institute for Child and Youth Health Care of Vojvodina, Sremska Kamenica, Serbia
2. Clinical Centre of Serbia, Neurosurgery Clinic, Belgrade, Serbia
3. University of Belgrade, Faculty of Medicine, Institute of Pathology, Belgrade, Serbia
4. University of Novi Sad, Faculty of Medicine, Institute of Oncology, Sremska Kamenica, Serbia