1. Department of Pediatrics, Centre of Postgraduate Medical Education, 99/103 Marymoncka Str., 01-813 Warsaw, Poland
2. Department of Pediatrics, Bielanski Hospital, 80 Cegłowska Str., 01-809 Warsaw, Poland
3. Student Research Group, Bielanski Hospital, 80 Cegłowska Str., 01-809 Warsaw, Poland