Propolypeptide of von Willebrand factor circulates in blood and is identical to von Willebrand antigen II - Fay, PJ; Kawai, Y; Wagner, DD; Ginsburg, D; Bonthron, D; Ohlsson-Wilhelm, BM; Chavin, SI; Abraham, GN; Handin, RI; Orkin, SH; Montgomery, RR; Marder, VJ (Science, 1986)