@misc{indiciae97b1e8e9df2d,
  title = {Aeromagnetic map of the western part of the Northern Peninsula, Michigan and part of northern Wisconsin},
  author = {Isidore Zietz and J.R. Kirby},
  year = {1971},
  doi = {10.3133/gp750},
  url = {https://pubs.usgs.gov/publication/gp750},
  note = {Source identifier: gp750}
}