@misc{indiciae72a9ad83c729,
  title = {Gravity field improvement using global positioning system data from TOPEX/Poseidon - A covariance analysis},
  author = {Bertiger, Willy I. and Wu, J. T. and Wu, Sien C.},
  year = {1992},
  url = {https://ntrs.nasa.gov/citations/19920042323},
  note = {Source identifier: 19920042323}
}