1) Dybkaer R & Graesbeck R: Theory of Reference Values. Scand J Clin Invest. 32: 1-7, 1973
2) Expert Panel on Theory of Reference Values (IFCC) : The Concept of Reference Values (1987) . Clin Chem 25: 1506-1508, 1989
3) NCCLS Document: How to Define, Determine and Utilize Reference Intervals in the Clinical Laboratory. Approved Guideline. NCCLS Document C29-A, 1995
4) ISO 15194: Measurement of Quantities in Samples of Diological Origin-Description of Reference Materials.
5) ISO 17511: Measurement of Quantities in Samples of Diological Origin-Metrological Traceability of Values Assigned to Calibrators and Control Materials.