@misc{indiciae7e884add03e3,
  title = {Preliminary aeromagnetic map (in color) covering most of the exposed Precambrian terrane in Wisconsin},
  author = {Isidore Zietz and John H. Karl and Meredith Eggers Ostrom},
  year = {1977},
  doi = {10.3133/ofr77598},
  url = {https://pubs.usgs.gov/publication/ofr77598},
  note = {Source identifier: ofr77598}
}