ESA's report to the 36th COSPAR meeting : Beijing, China, July 2006
Proceedings of the Seventh European Space Power Conference : 9-13 May 2005, Stresa, Italy
ESA's report to the 35th COSPAR meeting : Paris, France, July 2004
Proceedings of Space Propulsion 2004 : 2 - 9 June 2004, [Chia Laguna], Sardinia, Italy
ESA's report to the 34th COSPAR meeting : Houston, USA, October 2002