@misc{indiciaed76c3d41bc43,
  title = {A gravitational field model for the earth.},
  author = {Smith, D. E. and Lerch, F. J. and Wagner, C. A.},
  year = {1973},
  url = {https://ntrs.nasa.gov/citations/19730056524},
  note = {Source identifier: 19730056524}
}