Assay of von Willebrand factor (vWF)-cleaving protease based on decreased collagen binding affinity of degraded vWF. A tool for the diagnosis of thrombotic thrombocytopenic purpura (TTP) - Gerritsen,H.; Turecek,P.; Schwarz,H.P.; Lämmle,B.; Furlan,M. (Thromb Haemost, 1999)