@misc{indiciae7de5ba9b6ec2,
  title = {Bedrock topography of north-central Iowa},
  author = {R.E. Hansen},
  year = {1978},
  doi = {10.3133/i1080},
  url = {https://pubs.usgs.gov/publication/i1080},
  note = {Source identifier: i1080}
}