@misc{indiciaefb7e994d852a,
  title = {Description of data files compiled for the Central Midwest Regional Aquifer-System Analysis},
  author = {John O. Helgesen and Cristi V. Hansen},
  year = {1989},
  doi = {10.3133/ofr8942},
  url = {https://pubs.usgs.gov/publication/ofr8942},
  note = {Source identifier: ofr8942}
}