1. Sewage water, treated and untreated a heat source for heat pumps;Jacobsen,1981
2. Experiences with a 3.3 MW heat pump using sewage water as heat source;Lindstrom,1984
3. Alternative Drives for Heat Pumps, North Western Branch Papers;Reay,1981
4. Oppurtunities for gas engine driven heat pumps in the industrial and commercial markets;Masters,1980
5. Energy and economic comparisons of domestic heat pumps and conventional heating systems in the British Climate;Tassou;J. appl. Energy,1986