1. American Society of Heating, Refrigerating and Air Conditioning Engineers (1992). ANSI/ASHRAE 34-1992, Number designation and safety classification of refrigerants.
2. American Society of Heating, Refrigerating and Air Conditioning Engineers (1998). Third Public Review on BSR/ASHRAE addendum 34p to ANSI/ASHRAE 34p, Number designation and safety classification of refrigerants.
3. American Society for Testing and Materials (1994). ASTM E 681, Standard test method for concentration limits of flammability of chemicals.
4. Underwriters Laboratories (1996). UL 2182, Standard for refrigerants.