Role of B cells in chronic graft‐versus‐host disease after allogeneic stem cell transplantation in children and adolescents. (28th May 2019) - Wiegering, Verena; Keupp, Anne; Frietsch, Marieke; Fiessler, Cornelia; Haas, Kirsten; Haubitz, Imme; Beyersdorf, Niklas; Wölfl, Matthias; Schlegel, Paul‐Gerhardt; Eyrich, Matthias