@misc{indiciaee1033c8b06db,
  title = {Bedrock topography of northeast Iowa},
  author = {R.E. Hansen},
  year = {1975},
  doi = {10.3133/ofr7588},
  url = {https://pubs.usgs.gov/publication/ofr7588},
  note = {Source identifier: ofr7588}
}