@misc{indiciae88e91216f697,
  title = {Validation of GPS data-driven ionospheric specification models},
  author = {Wilson, B. D. and Hajj, G. and Pi, X. and Mannucci, A. and Rosen, G. and Wang, C.},
  year = {2001},
  url = {https://ntrs.nasa.gov/citations/20060040386},
  note = {Source identifier: 20060040386}
}