1. Ångström, A. K. andA. J. Drummond: Fundamental Principles and Methods for the Calibration of Radiometers for Photometric Use. J. Appl. Optics (in press).
2. Ångström, A. K., andA. J. Drummond: Basic concepts Concerning Cutoff Glass Filters Used in Radiation Measurements. J. Met.18, 360 (1961).
3. I. G. Y. Instruction Manual, V, Part VI, Radiation Instruments and Measurements, Table 7, p. 464. London: Pergamon Press. 1958.
4. Smithsonian Meteorological Tables, Sixth revised ed., Table 159, p. 449. Washington: Smithsonian Institution. 1951.
5. Linke's Meteorologisches Taschenbuch, New Ed.,2, Table 110, p. 524. Leipzig: Akademische Verlagsgesellschaft Geest und Portig K.-G.