@misc{indiciae09d38095c434,
  title = {Hydrologic Unit Map-1974, State of Iowa},
  author = {Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey},
  year = {1976},
  doi = {10.3133/hu15},
  url = {https://pubs.usgs.gov/publication/hu15},
  note = {Source identifier: hu15}
}