1. Blackwell, M. J.: Five Years' Continuous Recording of Daylight Illumination at Kew Observatory. Met. Res. Ctee., M. R. P. no. 831 (1953).
2. Blackwell, M. J.: Five Years' Continuous Recording of Total and Diffuse Solar Radiation at Kew Observatory. Met. Res. Ctee., M. R. P. no. 895 (1954).
3. Blackwell, M. J., andD. B. B. Powell: On the Development of an Improved Daylight Illumination Recorder. Met. Res. Ctee., M. R. P. no. 988 (1956).
4. Drummond, A. J.: Notes on the Measurement of Natural Illumination. I. Some Characteristics of Illumination Recorders. Arch. Met. Geoph. Biokl. B7, 437 (1956).
5. Ann. International Geophys. Year;International Union of Geodesy and Geophysics,1958