Confirmation of hepatitis C virus infection by new four-antigen recombinant immunoblot assay - van der Poel, CL; Cuypers, HTM; Reesink, HW; Weiner, AJ; Quan, S; di Nello, R; van Boven, JJP; Winkel, I; Mulder-Folkerts, D; Exel-Oehlers, PJ; Schaasberg, W; Leentvaar-Kuypers, A; Polito, A; Houghton, M; Lelie, PN (Lancet, 1991)