1. Barghausen , A. F. W. Finney L. L. Proctor L. D. Schultz Predicting long-term operational parameters of high-frequency skywave telecommunication systems Washington, D.C. 1969
2. Beckwith , R. I. A. D. Bailey N. N. Rao An investigation of directional propagation effects in high-frequency radio source location Urbana, Illinois 1972
3. Computation of HF backscatter amplitude;Croft;Radio Sci.,1967
4. Representation of diurnal and geographic variations of ionospheric data by numerical methods;Jones;J. Res. Nat. Bur. Stand., Sect. D,1962
5. Methods for applying numerical maps of ionospheric characteristics;Jones;J. Res. Nat. Bur. Stand., Sect. D,1962