1. Potential of Electrically Operated Heat Pumps for Heating Water in South Africa;Johannsen;CSIR Rept 615,1986
2. Die verwarming van huishoudelike water;Basson;National Building Research Institute, SCIR Rept,1983
3. Die markpotensiaal van hittepompe in Suid-Afrika;Greyvenstein,1990