@misc{indiciae57e919d01207,
  title = {Aeromagnetic map of Maryland},
  author = {Isidore Zietz and F. P. Gilbert and J. R. Kirby},
  year = {1978},
  doi = {10.3133/gp923},
  url = {https://pubs.usgs.gov/publication/gp923},
  note = {Source identifier: gp923}
}