1. Department of Pediatric Hematology and Oncology Children's Hospital; Hannover Medical School; Hannover Germany
2. Department of Pediatric Hematology and Oncology; University Children's Hospital Muenster; Muenster Germany
3. Department of Pediatrics; St. Anna Children's Hospital and Children's Cancer Research Institute; Medical University of Vienna; Vienna Austria
4. Department of Pediatric Hematology and Oncology, 2nd Faculty of Medicine; Charles University and University Hospital Motol; Prague Czech Republic
5. Department of Pediatric Oncology/Hematology; Charité University Medical Center Berlin; Berlin Germany
6. Department of Pediatric Hematology and Oncology; Justus-Liebig-University; Giessen Germany
7. Department of Pediatric Hematology-Oncology; University of Duisburg-Essen; Essen Germany