@misc{indiciae5489abce71fe,
  title = {Aeromagnetic map of the Fitchburg quadrangle, Worcester County, Massachusetts},
  author = {Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey},
  year = {1971},
  doi = {10.3133/gp739},
  url = {https://pubs.usgs.gov/publication/gp739},
  note = {Source identifier: gp739}
}