De Stefano, V, P Simioni, E Rossi, D Tormene, T Za, A Pagnan, and G Leone. 2006. “The Risk of Recurrent Venous Thromboembolism in Patients With Inherited Deficiency of Natural Anticoagulants Antithrombin, Protein C and Protein S”. Haematologica 91 (5). Pavia, Italy, 695-98. https://haematologica.org/article/view/3968.