@misc{indiciaee50eb00cee1e,
  title = {Total intensity aeromagnetic map of Blackford County, Indiana},
  author = {William J. Dempsey and John R. Henderson and R. T. Duffner},
  year = {1951},
  doi = {10.3133/gp52},
  url = {https://pubs.usgs.gov/publication/gp52},
  note = {Source identifier: gp52}
}