@misc{indiciae7a7dcd5ccc11,
  title = {Aeromagnetic map of Gladstone and vicinity, Delta, Alger, Menominee, and Marquette Counties, Michigan.},
  author = {Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey},
  year = {1969},
  doi = {10.3133/ofr69290},
  url = {https://pubs.usgs.gov/publication/ofr69290},
  note = {Source identifier: ofr69290}
}