@misc{indiciae63204408e657,
  title = {User's Guide for the Precision Recursive Estimator for Ephemeris Refinement (PREFER)},
  author = {Gibbs, B. P.},
  year = {1982},
  url = {https://ntrs.nasa.gov/citations/19830018253},
  note = {Source identifier: 19830018253}
}