@misc{indiciae258c196e55de,
  title = {A magnetic anomaly of possible economic significance in southeastern Minnesota},
  author = {Isidore Zietz},
  year = {1964},
  doi = {10.3133/cir489},
  url = {https://pubs.usgs.gov/publication/cir489},
  note = {Source identifier: cir489}
}