1. Charters WWS, Megler VR, Urma I, Lu Aye. Propane as a working fluid in domestic heat pumps. In: IIR/IIF-Melbourne 1996: Refrigeration, Climate Control and Energy Conservation. 1996 February 11-14; Melbourne, Australia. Melbourne: International Institute of Refrigeration, 1996.
2. Urma I. Propane as a replacement for domestic applications. MEngSc thesis, Department of Mechanical and Manufacturing Engineering, The University of Melbourne; 1997.
3. Comparison of ammonia with other refrigerants for district cooling plant chillers;Stoecker;ASHRAE Trans,1994
4. International Institute of Refrigeration (IIR). Proceedings of the Conference of Natural Working Fluids'98 IIR - Gustav Lorentzen Conference, 2–5 June 1998. Oslo, Norway.
5. HCFC-22 alternative for air conditioners and heat pumps;Bivens;ASHRAE Trans,1994