1. Potential of electrically operated heat pumps for heating water in South Africa;Johannsen;CSIR Report 615,1986
2. Die verwarming van huishoudelike water;Basson;National Building Research Institute, CSIR Report,1983
3. Die Markpotensiaal van Hittepompe in Suid-Afrika;Greyvenstein,1990
4. Energy efficiencies of heat pumps in residential buildings