IFCC reference system for measurement of hemoglobin A1c in human blood and the national standardization schemes in the United States, Japan, and Sweden: a method-comparison study - Hoelzel, W; Weykamp, C; Jeppsson, J O; Miedema, K; Barr, J R; Goodall, I; Hoshino, T; John, W G; Kobold, U; Little, R; Mosca, A; Mauri, P; Paroni, R; Susanto, F; Takei, I; Thienpont, L; Umemoto, M; Wiedmeyer, H M (Clin Chem, 2004)