@misc{indiciae446e61f2e1f8,
  title = {Gravitational field models for the earth (GEM 1 and 2)},
  author = {Lerch, F. J. and Wagner, C. A. and Smith, D. E. and Andson, M. L. and Brownd, J. E. and Richardson, J. A.},
  year = {1972},
  url = {https://ntrs.nasa.gov/citations/19720021773},
  note = {Source identifier: 19720021773}
}