Single agent bevacizumab for myelofibrosis: results of the Myeloproliferative Disorders Research Consortium Trial - Ruben A. Mesa; Richard T. Silver; Srdan Verstovsek; John Mascarenhas; Craig M. Kessler; Damiano Rondelli; Judy D. Goldberg; Roberto Marchioli; Erin P. Demakos; Lewis R. Silverman; Ronald Hoffman (Haematologica)