@misc{indiciaee5274d9e4965,
  title = {Aeromagnetic map of the Valley Forge quadrangle, Chester, Montgomery, and Delaware Counties, Pennsylvania},
  author = {Randolph Wilson Bromery and G. L. Zandle},
  year = {1959},
  doi = {10.3133/gp200},
  url = {https://pubs.usgs.gov/publication/gp200},
  note = {Source identifier: gp200}
}