Jehn, Rüdiger; Ariafar, Shahram; Schildknecht, Thomas; Musci, Reto; Oswald, Michael (2006). Estimating the Number of Debris in the Geostationary Ring. Acta astronautica, 59(1-5), pp. 84-90. Oxford: Pergamon 10.1016/j.actaastro.2006.02.053