1. Kaplan, M. H., Modern spacecrat dynamics and control, John Wiley & Sons, New York, 1976.
2. Colombo, O. L., Ephemeris errors of GPS satellites, Bull. Geod., Vol. 60, 64–84, 1986.
3. Cook, G.E., Perturbations of near-circular orbits by the earth's gravitational potential, Planetary and Space Sciences, Vol. 14, 434–444, 1966.
4. Hough, M. E., Orbits near critical inclination, including luni-solar perturbations, Celestial Mechanics, Vol. 25, 111–136, 1981.
5. Kaula, W.M., Theory of satellite geodesy. Blaisdell Publishing Co., 1966.