The role of chemotherapy in the treatment of children with neuroblastoma stage IV: the GPO (German Pediatric Oncology Society) experience - Berthold, F; Burdoch, S; Kremenes, B; Lam-pert, F; Niethammer, D; Riehm, A; Ritter, J; Treuner, J; Utsch, S; Zieschang, J (Klin Pediatr, 1990)