1. Gallet, R., Trans. Inst. Rad. Eng., on Antennas and Propagation (Astrophys., 5, 327, 1957).
2. Burke, B. F., Carnegie Inst. Wash. Yearbook, No. 56, 90 (1957).
3. Shain, C. A., Austral. J. Phys., 9, 61 (1956).
4. Carr, T. D., Smith, A. G., Pepple, R., and Barrow, C. H., Astrophys. J., 127, 274 (1958).
5. Franklin, K. L., and Burke, B. F., J. Geophys. Res., 63, 807 (1958).