Efficacy and safety of rivaroxaban vs warfarin in high-risk patients with antiphospholipid syndrome: rationale and design of the Trial on Rivaroxaban in AntiPhospholipid Syndrome (TRAPS) trial - Pengo, V; Banzato, A; Bison, E; Zoppellaro, G; Padayattil Jose, S; Denas, G (Lupus, 2016)