@misc{indiciae2448dc459ec3,
  title = {Gravity field improvement using GPS data from Topex/Poseidon - A covariance analysis},
  author = {Bertiger, Willy I. and Wu, J. T. and Wu, Sien C.},
  year = {1990},
  url = {https://ntrs.nasa.gov/citations/19900065966},
  note = {Source identifier: 19900065966}
}