1. Montreal Protocol on substances that deplete the ozone layer, United Nations (UN), New York, (USA), 1987.
2. United Nations Environment Programme (UNEP), Handbook for the international treaties for the protection of the ozone layer (5th ed.), Nairobi, Kenya, Ozone Secretariat, 2000.
3. Kyoto Protocol to the United Nations framework convention on climate change, United Nations (UN), New York, USA, 1997.
4. Calm JM, Didion DA. Trade-offs in refrigerant selections: past, present, and future. Refrigerants for the 21st Century, Atlanta, (GA), American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) 1997; 6-19, in Japanese (translation by S. Sakaida) in Reito, 73(847):433-444, May 1998; International Journal of Refrigeration, 1998 21(4):308-321.
5. Fluorocarbon refrigerants handbook;Downing,1988