Immunologic differentiation of classic haemophilia (Factor VIII deficiency) and von Willebrand’s disease with observations on combined deficiencies of antihaemophilic factor and proaccelerin (factor V) and on an acquired circulating anticoagulant against haemophilic factor - Zimmerman, T S; Ratnoff, O D; Powell, A E (J Clin Invest, 1971)