1. Final Report of EURAMET QM-S4 – Key comparison automotive gas mixture, VSL, September 2011.
2. International Organization for Standardization, ISO 6142:2001 Gas analysis - Preparation of calibration gas mixtures - Gravimetric methods, 2nd edition
3. International Organization for Standardization, “ISO 6143 – Gas analysis -- Comparison methods for determining and checking the composition of calibration gas mixtures”, ISO Geneva, 2001
4. The evaluation of key comparison data: An introduction
5. The evaluation of key comparison data