@misc{indiciaeafdff0a2f3eb,
  title = {Aeromagnetic map of northern Frederick County, Maryland, and parts of adjacent counties in Maryland and Pennsylvania},
  author = {Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey},
  year = {1973},
  doi = {10.3133/ofr73291},
  url = {https://pubs.usgs.gov/publication/ofr73291},
  note = {Source identifier: ofr73291}
}