1. Accredited Organisations Database (2014) Singapore Accreditation Council, Singapore. http://www.sac-accreditation.gov.sg/Pages/Homepage.aspx . Accessed 17 July 2014
2. SAC-SINGLAS Technical Notes PROF-001 Policies on Proficiency Testing (2014) Singapore Accreditation Council, Singapore. http://www.sac-accreditation.gov.sg/Resources/sac_documents/Documents/Calibration_and_Testing_Laboratories/Related_Documents/All_Fileds/PROF-001%20Tech%20Note%20(Apr%202014).pdf . Accessed 17 July 2014
3. ISO (2005) ISO 13528:2005 Statistical methods for use in proficiency testing by interlaboratory comparisons. International Organization for standardization (ISO), Geneva
4. Determining Consensus Value in Interlaboratory Comparisons and Proficiency Testing (2003) Nielsen H.S., Indianapolis. http://www.hn-proficiency.com/Determining%20Consensus%20Values%20in%20Interlaboratory%20Comparison%E2%80%A6.pdf . Accessed 17 July 2014
5. De Bièvre P (2012) Accred Qual Assur 17:561–562