1. http://www.gpoaccess.gov/cfr/index.html
2. “Mutual recognition of national measurement standards and of calibration and measurement certificates issued by national metrology institutes,” CIPM, Paris (1999)
3. http://ts.nist.gov/Standards/upload/What-is-the-NVLAP.pdf
4. http://ts.nist.gov/Standards/Accreditation/handbook.cfm
5. http://ts.nis.gov/Traceability/nist_traceability_policy-external.cfm