1. Cornell, G., 1998. Visual Basic 6, 1st Edition. McGraw-Hill Libri Italia, Milano, 866pp.
2. Davies, K., 1990. Ionospheric Radio. IEE Electromagnetic Waves Series 31. Peter Peregrinus Ltd., London, UK, 580pp.
3. Automatic scaling of digital ionograms;Fox;Radio Science,1989
4. Automatic ionogram processing system. 2. Automatic Ionogram Scaling;Igi;Journal of the Communication Laboratory,1992
5. Piggott, W.R., Rawer, K., 1972. U.R.S.I. Handbook of Ionogram Interpretation and Reduction. U.S. Department of Commerce National Oceanic and Atmospheric Administration—Environmental Data Service, Asheville, North Carolina, USA, 326pp.