Nørgaard Jensen , O., N. de Fine Olivarius, P. Hyltoft Petersen, N. A. Klitgaard, O. Blaabjerg, and M. Hørder. “6.1.1.1 Discrepancy in HbA1c Measurements Performed at Different Local Laboratories and at a Selected Central Reference Laboratory”. Upsala Journal of Medical Sciences, vol. 98, no. 3, Sept. 1993, pp. 275-82, doi:10.3109/03009739309179321.