1. Martyn, D. F., Proc. Second Meeting Mixed Comm. on Ionosphere, I.C.S.U., Brussels, 44, (1950). (Corrigendum note: on p. 45, line 31 of this report “maximum”, should read “minimum”).
2. Skinner, N. J., and Wright, R. W., Proc. Phys. Soc., B, 70, 833 (1957).
3. Martyn, D. F., Phil. Trans. Roy. Soc., 246, 306 (1953).
4. Martyn, D. F., Proc. Inst. Rad. Eng., 47, 147 (1959).
5. Clemmow, P. C., Johnson, M. A., and Weekes, K., “Physics of the Ionosphere”, Phys. Soc. (Lond,)., 136 (1955).