@misc{indiciaeb890c3d719ee,
  title = {Aeromagnetic map of Virginia},
  author = {Isidore Zietz and J.L. Calver and S.S. Johnson},
  year = {1977},
  doi = {10.3133/gp916},
  url = {https://pubs.usgs.gov/publication/gp916},
  note = {Source identifier: gp916}
}