@misc{indiciae34f7d4867b9e,
  title = {Bedrock topography of north-central Iowa},
  author = {R.E. Hansen},
  year = {1977},
  doi = {10.3133/ofr77174},
  url = {https://pubs.usgs.gov/publication/ofr77174},
  note = {Source identifier: ofr77174}
}