A comparison of six weeks with six months of oral anticoagulant therapy after a first episode of venous thromboembolism - Schulman, S; Rhedin, AS; Lindmarker, P; Carlsson, A; Larfars, G; Nicol, P; Loogna, E; Svensson, E; Ljungberg, B; Walter, H; Viering, S; Norlander, S; Leijd, B; Jonsson, KA; Hjorth, M; Linder, O; Boberg, J (N Engl J Med, 1995)