@misc{indiciaedc86385660db,
  title = {Summary appraisals of the nation's ground-water resources – Upper Mississippi region},
  author = {R. M. Bloyd},
  year = {1975},
  doi = {10.3133/pp813b},
  url = {https://pubs.usgs.gov/publication/pp813B},
  note = {Source identifier: pp813B}
}