@misc{indiciaefd570157edc7,
  title = {Aeromagnetic map of the Birdsboro quadrangle, Berks County, Pennsylvania},
  author = {Randolph Wilson Bromery and J. R. Henderson and G. L. Zandle},
  year = {1960},
  doi = {10.3133/gp231},
  url = {https://pubs.usgs.gov/publication/gp231},
  note = {Source identifier: gp231}
}