1. International Frequency Registration Board (IFRB) Circular 1522, special section no. AR 11/A/3, International Telecommunications Union (ITU). Geneva, 1982.
2. ‘The Transit navigation satellite system’, Magnavox Advanced Products Division, Torrance, CA, U.S.A., October 1978.
3. The Russian satellite navigation system
4. NAVSTAR GPS special issue, Navigation, Vols I (1980), II (1984) and III (1987).