Pretreatment prognostic factors and treatment results in children with hepatoblastoma: a report from the German Cooperative Pediatric Liver Tumor Study HB 94 - Fuchs, J; Rydzynski, J; Von Schweinitz, D; Study Committee of the Cooperative Pediatric Liver Tumor Study Hb 94 for the German Society for Pediatric Oncology and Hematology (Cancer, 2002)