F Piovella, L Crippa, M Barone, S Vigano D’Angelo, S Serafini, L Galli, C Beltrametti, A D’Angelo. Normalization rates of compression ultrasonography in patients with a first episode of deep vein thrombosis of the lower limbs: association with recurrence and new thrombosis. Haematologica 2002; 87(5):515-522.