@misc{indiciae6765b5989eb6,
  title = {Map of east-central South Dakota showing area, underlain by more than 25 feet of stratified sand and gravel},
  author = {J.R. Jones},
  year = {1956},
  doi = {10.3133/ofr5664},
  url = {https://pubs.usgs.gov/publication/ofr5664},
  note = {Source identifier: ofr5664}
}