1. 1) Soop, E. M.: Handbook of Geostationary Orbits, Section 5.6, Kluwer, Dordrecht, Netherlands, 1994.
2. 4) Wauthier, P., Bischops, E., Francken, P., Hooghe, M. and Laroche, H.: On the Co-Location of Eight ASTRA Satellites, Proceedings of the 15th International Symposium on Space Flight Dynamics, Biarritz, France, 2000, MS00/41.
3. Autonomous ring formation for a planar constellation of satellites