@misc{indiciaeeb0fcc9352a3,
  title = {Principal facts for gravity stations in Maryland, northern Virginia, southern Pennyslvania and the District of Columbia},
  author = {D. L. Daniels},
  year = {1990},
  doi = {10.3133/ofr90265},
  url = {https://pubs.usgs.gov/publication/ofr90265},
  note = {Source identifier: ofr90265}
}