1. EURACHEM: Selection, Use and Interpretation of Proficiency Testing (PT) Schemes by Laboratories (2000)
2. ISO Guide 43–1, Proficiency testing by interlaboratory comparisons–Part 1: Development and operation of proficiency testing schemes.
3. ISO Guide 43–2, Proficiency testing by interlaboratory comparisons–Part 2: Selection and use of proficiency testing schemes by laboratory accreditation bodies.
4. Thompson, M., and Wood, R.: The international harmonized protocol for proficiency testing of (chemical) analytical laboratories. J. AOAC Int. 76, 926 (1993).
5. International laboratory accreditation cooperation: G-13, Guidelines for the requirements for the competence of providers of proficiency testing schemes. Available from the ILAC-homepage http://www.ilac.org.