Allogeneic versus autologous stem cell transplantation after relapsing following first line autologous transplantation for multiple myeloma: A systematic review. - Ludwig H; Bernhard S; Ikeda T; Freytes CO; Schreder M; Kawamura K; Atsuta Y; Takamatsu H; Vesole DH; Hari P; Krainer J; Hinke A (Cancer, 2025)