1. ISO/IEC 17025:2005 General requirements for the competence of testing and calibration laboratories. International Standardization Organization (ISO), Geneva, Switzerland
2. ISO/IEC DIS 17025:2016(E) General requirements for the competence of testing and calibration laboratories. International Standardization Organization (ISO), Geneva, Switzerland
3. ISO/IEC 17011:2004 Conformity assessment. General requirements for accreditation bodies accrediting conformity assessment bodies. International Standardization Organization (ISO), Geneva, Switzerland
4. ILAC P9:06/2014 ILAC Policy for participation in proficiency testing activities. International Laboratory Accreditation Cooperation (ILAC).
http://ilac.org/publications-and-resources/
5. EA 4/18 INF:2010 Guidance on the level and frequency of proficiency testing participation. European Accreditation (EA).
http://www.european-accreditation.org/publication/ea-4-18-inf-rev00-june-2010-rev