@misc{indiciae2d8cfc263bac,
  title = {Gravity field determination and error assessment techniques},
  author = {Yuan, D. N. and Shum, C. K. and Tapley, B. D.},
  year = {1989},
  url = {https://ntrs.nasa.gov/citations/19900011201},
  note = {Source identifier: 19900011201}
}