1.   Jeppsson JO, Kobold U, Barr J, Finke A, Hoelzel W, Hoshino T, Miedema K, Mauri P, Mosca A, Paroni R, Thienpont L, Umemoto M, Weykamp CW. Approved IFCC reference method for the measurement of HbA1c in human blood. Clin Chem Lab Med 2002;40:70-89.
2.   Hoelzel W, Weykamp C, Jeppsson JO, Miedema K, Barr JR, Goodall I, Hoshino T, John WG, Kobold U, Little R, Mosca A, Mauri P, Paroni R, Susanto F, Takei I, Thienpont L, Umemoto M, Wiedmeyer HM. 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. Clin Chem 2004;50:166-74.
3.   Cas Weykamp, W Garry John, Andrea Mosca, Tadao Hoshino, Randie Little, Jan-Olof Jeppsson, Ian Goodall, Kor Miedema, Gary L. Myers, Hans Reinauer, David B. Sacks, Robbert Slingerland and Carla Siebelder. The IFCC Reference Measurement System for HbA1c: A 6-Year Progress Report. Clin Chem 2008;54:240-8.
4.   Weykamp C, John G, Gillery P, English E, Ji L, Lenters-Westra E, Little RR, Roglic G, Sacks DB, Takei I; IFCC Task force on Implementation of HbA1c Standardization. Investigation of 2 models to set and evaluate quality targets for HbA1c: biological variation and sigma-metrics. Clin Chem 2015;61:752-9.
5.   Andrea Konnert, Christoph Berding, Sabine Arends, Curt Parvin, Curt L. Rohlfing, Hsiao-Mei Wiedmeyer, Randie Little, Carla Siebelder, Cas Weykamp. Statistical Rules for Laboratory Networks. Journal of Testing and Evaluation 2006;34: 128-34.
6.   Andrea Konnert, Sabine Arends, Stefan Schubert, Christoph Berding, Cas Weykamp, Carla Siebelder. Uncertainty calculation for calibrators of the IFCC HbA1c standardization network. Accred Qual Assur 2006;11:319-328.
7.   Andrea Geistanger, Sabine Arends, Christoph Berding, Tadao Hoshino, Jan-Olof Jeppsson, Randie Little, Carla Siebelder and Cas Weykamp on behalf of the IFCC Working Group on Standardization of HbA1c: Statistical Methods for Monitoring the Relationship between the IFCC Reference Measurement  Procedure for Hemoglobin A1c and the Designated Comparison Methods in the United States, Japan and Sweden. Clin Chem 2008;54:1379-85.
8.   Patricia Kaiser, Theodorus Akerboom, Petra Molnar, Hans Reinauer. Modified HPLC-Electrospray Ionization/Mass Spectrometry Method for HbA1c Based on IFCC Reference Measurement Procedure. Clin Chem 2008;54:1018-22.
9.   John WG. Haemoglobin A1c interpretation; more than mean blood glucose tob e considered. Diabet Med 2017;34:751-2.
10.   Lenters-Westra E, Slingerland R. Three of 7 hemoglobin A1c point-of-care instruments do not meet generally accepted analytical performance criteria. Clin Chem 2014;60:1062-72.
11.   English E, Idris I, Smith G, Dhatariya K, Kilpatrick ES, John WG. The effect of anaemia and abnormalities of erythrocyte indices on HbA1c analysis: a systematic review. Diabetologia 2015;58:1409-21.
12.   Cas W. Weykamp, Andrea Mosca, Philippe Gillery, Mauro Panteghini. The Analytical Goals for hemoglobin A1c measurement in IFCC Units and National Glycohemoglobin Standardization Program Units are different. Clin Chem 2011;57:1204-5.
13.   Mosca A, Paleari R, Carobene A, Weykamp C, Ceriotti F. Performance of glycated hemoglobin (HbA1c) methods evaluated with EQAS studies using fresh blood samples: Still space for improvements. Clin Chim Acta 2015;451:305-9.
14.   John WG. Global standardization of haemoglobin A(1c) using metrological principles. Clin Biochem 2012;45:1048-50.
15.   Kaiser P, Spannagl M, van Campenhout C, Lenga Y, Siebelder C, Weykamp C. HbA1c: EQA in Germany, Belgium and the Netherlands using fresh whole blood samples with target values assigned with the IFCC reference system. Clin Chem Lab Med 2016;54 (11):1769-1775
16.   Lenters-Westra E, english E. Understanding the use of sigma Metrics in Hemoglobin A1c analysis. Clin Lab Med 2017;37:57-71.
17.   Little RR, La’ulu SL, Hanson SE, Rohlfing CL, Schmidt RL. Effects of 49 different rare Hb Variants on HbA1c measurement in eight methods. J diabetes Sci Technol 2015;9:849-56
18.   Weykamp C, siebelder C. Evaluation of performance of laboratories and manufacturers within the framework of the IFCC model for Quality Targets. J Diabetes Sci Technol 2018;12(4):747-752.
19.   EurA1c Trial Group. EurA1c: the European HbA1c Trial to Investigate the Performance of HbA1c Assays in 2166 Laboratories across 17 Countries and 24 Manufacturers by Use of the IFCC Model for Quality Targets. Clin Chem 2018;64(8):1183-1192