1. Thompson M, Wood R (1995) Pure Appl Chem 67:649–666
2. ISO/IEC Guide 43-1:1997. Proficiency testing by interlaboratory comparisons—Part 1: Development and operation of proficiency testing schemes. International Organization for Standardization, Geneva, Switzerland
3. ISO 13528:2005 Statistical methods for use in proficiency testing by interlaboratory comparisons. International Organization for Standardization, Geneva, Switzerland
4. ILAC-G13:2000 Guidelines for the requirements for the competence of providers of proficiency testing schemes. Available at http://www.ilac.org/
5. Thompson M, Ellison SLR, Wood R (2006) Pure Appl Chem 78:145–196. Available at http://www.iupac.org