1. European Co-operation for Accreditation, The Selection and Use of Reference Materials, EA-04/14, European Accreditation, February 2003.
2. ILAC, Guidelines for the Requirements for the Competence of Providers of Proficiency Testing Schemes, ILAC-G13, 2000.
3. ISO/IEC, Proficiency Testing by Interlaboratory Comparisons, Part 1: Development and Operation of Proficiency Testing Schemes, ISO/IEC Guide 43-1, 1997.
4. ISO/IEC, General Requirements for the Competence of Reference Material Producers, ISO/IEC Guide 34, 2000.
5. US Food and Drug Administration, Bioanalytical Method Validation: Guidance for Industry, Center for Drug Evaluation and Research (CDER), Rockville, May 2001.