1. Radio Waves in the Ionosphere;Budden,1961
2. Ray tracing in the ionosphere;Kelso;Radio Sci.,1968
3. The propagation of sound in an inhomogeneous and moving medium I;Blokhintzev;J. Acoust. Soc. Am.,1945
4. A Versatile Three-Dimensional Ray Tracing Computer Program for Radio Waves in the Ionosphere;Michael Jones,1975
5. Theoretical eye model with aspherics;Lotmar;J. Opt. Soc. Am.,1971