Dimopoulos MA, Beksac M, Benboubker L, Roddie H, Allietta N, Broer E, Couturier C, Mazier M-A, Angermund R, Facon T. Phase II study of bortezomib-dexamethasone alone or with added cyclophosphamide or lenalidomide for sub-optimal response as second-line treatment for patients with multiple myeloma. Haematologica [Internet]. 2013;98(8):1264 - 1272.