1. The search for debris in GEO
2. 3) Schildknecht, T., Musci, R., Ploner, M., de Leon Cruz, J. and de Fatima Dominguez Palmero, L.: Optical Survey for Space Debris in GEO, Space Debris 2001, Sciences and Technology Series, Vol. 105, Bendisch J. (ed.), Univelt Inc., San Diego, California, USA, 2002, pp. 9–21.
3. Optical observations of space debris in GEO and in highly-eccentric orbits
4. 5) Johnson, N. L., Whitlock, D. O., Anz-Meador, P., Cizek, M. E. and Portman, S. A.: History of On-Orbit Satellite Fragmentations, 13th ed., Orbital Debris Program Office, JSC 62530, Johnson Space Center, NASA, Houston, Texas, USA, May 2004, pp. 11–22.