1) GB7599 and GB/T 264 Test Methods for Acid Number in Operational Transformer Oil and Turbine Oil
2) JIS-C2101-1999 Test Method for Electrical Insulating Oil
3) JPI-5S-57-99 Japan Petroleum Institute - Neutralization Test Method for Electrical Insulating Oil - Total Acid Number Indicator Photometric Titration
4) ASTM D974 - 06 Standard Test Method for Acid and Base Number by Color Indicator Titration
5) BS148 - 1998 Specification for Unused and Reclaimed Mineral Insulating Oils for Transformers and Switchgear