@misc{indiciaec43371ce1b20,
  title = {GPS and Ionosphere},
  author = {Mannucci, A. and Iijima, B. and Lindqwister, U. and Pi, X. and Sparks, L. and Wilson, B.},
  year = {1999},
  url = {https://ntrs.nasa.gov/citations/20060040559},
  note = {Source identifier: 20060040559}
}