1. M. Anastassiades, D. Ilias, C. Caroubalos, C. Macris, and D. Elias, Nature 201, 357 (1964).
2. M. Anastassiades and P. Giouleas, Scientific Report No, IIA 005 (Ionospheric Institute, National Observatory of Athens, June 1963 ).
3. E. Appleton and W. R. Piggot, Atmospheric Terres. Phys. 5, 141 (1954).
4. K. A. Sarada and A. P. Mitra, Results of Cosmic Noise Observations at Delhi on 22.4 Mc/s (private communication).
5. M. Anastassiades, Radio Astronomical and Satellite Studies of the Atmosphere (North Holland Publishing Co., Amsterdam, 1963), p. 238, J. Aarons, ed.