@misc{indiciaeb55eedbbbbfb,
  title = {Aeromagnetic map of southeastern Minnesota},
  author = {P. W. Philbin and F. P. Gilbert},
  year = {1966},
  doi = {10.3133/gp559},
  url = {https://pubs.usgs.gov/publication/gp559},
  note = {Source identifier: gp559}
}