1. Aragón A, Orús R, Amarillo F, Hernández-Pajares M, Juan JM, Sanz J (2004) Performance of NeQuick ionospheric predictions compared with different ionospheric data. Presented at ESTEC/ESA Navitech’04, Noordwijk
2. Azpilicueta F, Brunini C, Radicella S (2005) Global ionospheric maps from GPS observations using modip latitude. JASR. doi: 10.1016/j.asr.2005.07.069
3. Bishop G, Walsh D, Daly P, Mazzella A, Holland E (1994) Analysis of the temporal stability of GPS and GLONASS group delay correction terms seen in various sets of ionospheric delay data. In: Proceeding of the ION GPS-94, pp 1653–1661
4. Brown RG, Hwang PYC (1992) Introduction to random signals and applied Kalman filtering, 2nd edn. Wiley, London
5. Brunini C, Meza A, Gende M, Azpilicueta F (2007) South American regional ionospheric maps computed by GESA: a pilot service in the framework of SIRGAS. JASR 42: 737–744. doi: 10.1016/j.asr.2007.08.041