The effect of activated prothrombin-complex concentrate (FEIBA) on joint and muscle bleeding in patients with hemophilia A and antibodies to factor VIII: a double-blind clinical trial - Sjamsoedin, L J; Heijn, L; Mauser-Bunschoten, E P; van Gerijlswijk, J L; van, Houwelingen; van Asten, P; Sixma, J J (N Engl J Med, 1981)