1. Probability design of a solar supplemented heat pump system for multiple farmstead applications;Gupta,1980
2. The state of development and introduction of the heat pump in Austria;Reichl,1975
3. Heat Pumps;Heap,1979
4. Bivalent (hybrid) heat pump-oil heating systems for greenhouses;Tunc;Heat Recovery Systems,1985
5. An inexpensive and reliable solar water heater for Jordan;Al-saad;Dirasat,1986