1. Fox , M. W. Automatic ionogram scaling at IPS Tech. Rep Darlinghurst, New South Wales, Australia 1988
2. McCue , C. G. J. D. Gilbert Automatic ionogram scaling Boulder, Colo. 1988
3. Paul , A. K. Processing of digital ionograms San Diego, Calif. 1982
4. Piggott , W. R. K. Rawer U.R.S.I. handbook of ionogram interpretation and reduction 2nd ed. Boulder, Colo. 1972
5. Automatic calculation of electron density profiles from digital ionograms, 3, Processing of bottomside ionograms;Reinisch;Radio Sci.,1983