1. University Desk Encyclopedia, Elsevier, New York, 1977.
2. 2Agrawal,B.N.,Design of Geosynchronous Spacecraft, Prentice-Hall,Upper SaddleRiver, NJ, 1986.
3. 3Clarke, A. C. "Extra Terrestrial Relays," Wireless World, Oct.1945.
4. The Geostationary Applications Satellite