1. Orbital Behavior of Earth Satellites;Roberson;Jour. Franklin Inst.,1957
2. Die Säkularstörungen einer Aussenstationsbahn;Krause,1952
3. The Effect of the Earth's Oblateness on the Orbit of a Near Satellite;King-Hele;Royal Aircraft Establishment TN #GW 475,1957
4. On the Anomalies in the Movement of the Perigee Due to Oblateness and Air Drag for Critical Values of the Inclination;Breakwell,1959
5. T. Kozai, Special Report No. 22, Smithsonian Institution Astrophysical Observatory.