1. Anselmi A, Cesare S, Visser P, Van Dam T, Sneeuw N, Gruber T, Altes B, Christophe B, Cossu F, Ditmar P, Murboeck M, Parisch M, Renard M, Reubelt T, Sechi G, Texieira Da Encarnacao JG (2011) Assessment of a next generation gravity mission to monitor the variations of Earth’s gravity field. ESA Contract No. 22643/09/NL/AF, Executive Summary, Thales Alenia Space report SD-RP-AI-0721, March 2011
2. Bender P, Wiese D, Nerem R (2008) A possible dual-GRACE mission with 90 degree and 63 degree inclination orbits, paper presented at third international symposium on formation flying, Eur. Space Agency, Noordwijk, Netherlands, 23–25 April
3. Christophe B, Marque J-P, Foulon B (2010) Accelerometers for the ESA GOCE Mission: one year of in-orbit results. Presentation at EGU 2010, Vienna. ESA GOCE website. http://earth.esa.int/pub/ESA_DOC/GOCE/Accelerometers%20for%20the%20ESA%20GOCE%20Mission%20-%20one%20year%20of%20in-orbit%20results.pdf . Accessed on 24 September 2012
4. Coddington I, Swann WC, Nenadovic L, Newbury NR (2009) Rapid and precise absolute distance measurements at long range. Nature Photonics 3:351–356. doi: 10.1038/nphoton.2009.94
5. Elsaka B (2010) Simulated satellite formation flights for detecting the temporal variations of the earth’s gravity field. University of Bonn, Germany, Ph.D Dissertation