1. GPS-Satellites of opportunity for ionospheric monitoring;Coco;GPS World,1991
2. Ionospheric slab thickness in middle and low latitudes;Davies;Radio Sci.,1991
3. Total electron content and ionospheric slab thickness measurements using GPS satellites;Goodwin,1992
4. Potential limitations in making absolute ionospheric measurements using dual frequency radio waves from GPS satellites;Klobuchar,1993
5. The slab thickness of the mid-latitude ionosphere;Titheridge;Planet. Space Sci.,1973