1. Working Group B (WG-B) of the International Committee on GNSS (ICG) (2018) The interoperable global navigation satellite systems space service volume. Publishing and Library Section of United Nations Office , Vienna, pp 1–35
2. Enderle W, Schoenemann E (2017) GNSS space service volume & user perspective. Munich Satellite Navigation Summit 2017, Munich, Germany, pp 1–5
3. Enderle W, Schmidhuber M, Gill E, Montenbruck O, Braun A, Lemke N, Balbach O, Eisfeller B (1998) GPS performance for GEOs and HEOs: the EQUATOR-S spacecraft mission. In: Thirteenth international symposium on space flight dynamics. Goddard Space Flight Center, Greenbelt Maryland, United States, p 1
4. Winternitz LB, Bamford WA, Price SR, Carpenter JR, Long AC, Farahmand M (2017) Global positioning system navigation above 76,000 km for NASA’S magnetospheric multiscale mission, vol 64, pp 289–300
5. Filippi H, Gottzein E, Kuehl C, Mueller C, Barrios-Montalvo A, Dauphin H (2010) Feasibility of GNSS receivers for satellite navigation in GEO and higher altitudes. In: 2010 5th ESA workshop on satellite navigation technologies and European workshop on GNSS signals and signal processing (NAVITEC), Noordwijk, pp 1–8