1. Lawn RE, Thompson M, Walker RF (1997) Proficiency testing in analytical chemistry. The Royal Society of Chemistry, Cambridge, pp 55?56. ISBN 0-85404-432-9
2. Örnemark U, Boley N, Saeed K, Van Berkel PM, Schmidt R et al. (2001) Accred Qual Assur 6:140?146
3. A2LA (2001) Proficiency testing requirements for accredited testing and calibration laboratories, www.a2la2.net
4. Fostel H, Straub R (May 2003) Results on inquiry: EA/Eurachem/Eurolab (EEE)-PT Inquiry on the use of proficiency testing in accreditation procedures. Doc EEE/PT(03)08
5. ISO/IEC 17011 (draft 2002) General requirements for accreditation bodies accrediting conformity assessment bodies