@misc{indiciae82db9671362c,
  title = {Aeromagnetic map of part of the Marblehead North quadrangle, Essex County, Massachusetts},
  author = {Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey},
  year = {1970},
  doi = {10.3133/gp723},
  url = {https://pubs.usgs.gov/publication/gp723},
  note = {Source identifier: gp723}
}