1. Davies , K. Ionospheric Radio PropagationNBS Monograph 80 1965
2. Über den Weltumlauf der Radiostrahlen;Chvojková;Bull. Astron. Inst. Czechoslovakia,1954
3. Chvojková , E. Radio communication in astronautics in Russian Astron. Inst. Czechoslovakia Publ. 49 1963
4. Radio path formulae for radio-astronomy and astronautics;Chvojková;Bull. Astron. Inst. Czechoslovakia,1965
5. Analytical formulas for radio paths in spherically stratified ionospheres;Woyk;Radio Sci.,1965