REFERENCES
- Budden (K G). Radio waves in the Ionosphere. Cambridge University Press, New York, 1966.
- Davies (K). Ionospheric Radio Propagation. Dover Publication, Inc. New York, 1966.
- Croft (TA). Exact Ray calculation Radio Science, Vol. 3 Jan. 1968.
- Kelso (J M). Ray tracing in the Ionosphere, Rado Science, Vol. 3, Jan. 1968.