@misc{indiciaec4b1a1712acb,
  title = {Principal facts for gravity stations in Howard County, Maryland},
  author = {John Wing Allingham},
  year = {1970},
  doi = {10.3133/ofr704},
  url = {https://pubs.usgs.gov/publication/ofr704},
  note = {Source identifier: ofr704}
}