1. ANSI/ARI Standard 540-1999, 1999. Positive displacement refrigerant compressors and compressor units.
2. ARI Standard 210/240-2003, 2003. Unitary air-conditioning and air-source heat pump equipment.
3. ASHRAE Handbook, 2000. HVAC Systems and Equipment (Chapter 21 and 35).
4. Bertsch, S.S., 2005. Theoretical and Experimental Investigation of a Two Stage Heat Pump Cycle for Nordic Climates. Master's thesis, Mechanical Engineering, Herrick Labs 2005-13P, Report No. 7031-1, Purdue University, West Lafayette, Indiana, 2005.
5. Bertsch, S.S., Groll, E.A., 2005. Air to water heat pump for low temperature climates. In: 8th International Energy Agency Heat Pump Conference, Las Vegas, NV, CD-ROM.