1. Hottel, H. C. andA. Whillier: The evaluation of flat-plate solar collector performance. In press. (A brief outline of the main features of this paper may be found in “Solar Energy Research” (The University of Wisconsin Press, Madison, 1955), pages 50 to 56.)
2. Drummond, A. J. andE. N. van Deventer: The atmospheric transmission of solar radiation over Southern Africa. Notos, South African Weather Bureau, Pretoria. Vol. 3, No. 4, 1954.
3. Report for the Year 1951. South African Weather Bureau, Department of Transport, Pretoria.
4. Drummond, A. J. andJ. D. Wentzel: Actinometric Measurements and the Radiation Climate of South-West Africa. Arch. Met. Geoph. Biokl. B6, 236 (1955).