@misc{indiciaeb413df2bb9f5,
  title = {Black and white composite magnetic anomaly map of the United States: Part A, conterminous United States},
  author = {Isidore Zietz},
  year = {1983},
  doi = {10.3133/gp960a},
  url = {https://pubs.usgs.gov/publication/gp960A},
  note = {Source identifier: gp960A}
}