1. K. Davies, Ionospheric Radio Propagation, Monograph 80, National Bureau of Standards, Washington, D.C., 1 April 1965.
2. CCIR Report 322 (1964), World Distributions and Characteristics of Atmospheric Noise.
3. R.H. Barker, Group Synchronizing of Binary Digital Systems, in “Communication Theory,” Butterworth, London, 1953, pp 273–287.
4. D.C. Coll & J.R. Storey, Ionospheric Sounding Using Coded Pulse Signals, Rad. Sci. J. of Research, Vol. 68D(10), 1964, pp 1155–1159.
5. H.B. Mann, (Editor), Error Correcting Codes, Wiley, 1968, pp 195 – 225.