1. Blanch J, Walter T, Enge P (2002) Application of spatial statistics to ionosphere estimation for WAAS. In: On the CD-ROM of the proceedings of the National Technical Meeting of the Institute of Navigation. San Diego
2. Enge P, Walter T, Pullen S, Kee C, Chao YC, Tsai Y-J (1996) Wide area augmentation of the global positioning system. Proc IEEE 84:1063?1088
3. GIPSY, GPS-Inferred Positioning System (2004). http://gipsy.jpl.nasa.gov/orms/goa/
4. Iijima BA, Harris IL, Ho CM, Lindqwister UJ, Mannucci AJ, Pi X, Reyes MJ, Sparks LC, Wilson BD (1999) Automated daily process for global ionospheric total electron content maps and satellite ocean altimeter ionospheric calibration based on global positioning system. J Atmos Solar Terrestrial Phys 61:1205?1218
5. Komjathy A, Wilson BD, Runge TF, Boulat BM, Mannucci AJ, Sparks L, Reyes MJ (2002) A new ionospheric model for wide area differential GPS: the multiple shell approach. In: On the CD-ROM of the proceedings of the National Technical Meeting of the Institute of Navigation. San Diego