1. Department of Pediatric Hematology and Oncology; Medical University of Silesia; Zabrze Poland
2. Division of Hematology; Chorzów Center of Pediatrics and Oncology; Chorzów Poland
3. Department of Pediatric Hematology and Oncology; Medical University of Warsaw; Poland
4. Department of Pediatric Hematology; Oncology and Transplantology, University of Medical Sciences; Poznań Poland
5. Department of Pediatric Hematology; Oncology and Endocrinology, Medical University; Gdansk Poland
6. Department of Pediatrics; Medical University of Silesia; Katowice Poland
7. Department of Pediatric Hematology and Oncology; Medical University; Lublin Poland
8. Department of Microbiology and Immunology; Medical University of Silesia; Zabrze Poland