1. Department of Paediatrics; Faculty of Medicine; University of Crete; University Hospital Heraklion; Crete; Greece
2. Department of Hygiene; Epidemiology and Medical Statistics; Athens University Medical School; Athens; Greece
3. 4th Department of Paediatrics; School of Medicine; General Hospital Papageorgiou; Aristotle University of Thessaloniki; Thessaloniki; Greece