1. The orbital tower: a spacecraft launcher using the Earth's rotational energy;Pearson;Acta Astronautica,1975
2. Some aspects related to the statellite applications in non-stationary 24-hour orbits;Kumar;Acta Astronautica,1982
3. A solar altitude controller for extending operational life-span of communications satellites;Kumar;Acta Astronautica,1988
4. On the dynamic equilibrium of a special class of geostationary satellite systems;Stuiver,1987
5. The space elevator: thought experiment or key to the Universe;Clarke;Earth orient. Applic. Space Technol.,1981