@misc{indiciae3aaf9f5188f6,
  title = {Total intensity aeromagnetic map of Porter County, Indiana},
  author = {William J. Dempsey and John R. Henderson and R. T. Duffner},
  year = {1950},
  doi = {10.3133/gp30},
  url = {https://pubs.usgs.gov/publication/gp30},
  note = {Source identifier: gp30}
}