@misc{indiciae99c935562f87,
  title = {Satellite-satellite tracking for estimating geopotential coefficients.},
  author = {Martin, C. F. and Martin, T. V. and Smith, D. E.},
  year = {1972},
  url = {https://ntrs.nasa.gov/citations/19730029992},
  note = {Source identifier: 19730029992}
}