Immunological differentiation of classic hemophilia (factor VIII deficiency) and von Willebrand’s disease with some observations on combined deficiencies of antihemophilic factor and proaccelerin (factor V) and on an acquired circulating anticoagulant against antihemophilic factor - Zimmerman, T. S; Ratnoff, O. D; Powell, A. E (J. clin. Invest, 1971)