Detection of deep vein thrombosis by real-time B-mode ultra-sonography - Lensing, AWA; Prandoni, P; Brandjes, DPM; Huisman, PM; Vigo, M; Tomas-sella, G; Krekt, J; ten Cate, JW; Huisman, MV; Büller, HR (N Engl J Med, 1989)