@misc{indiciae983c6e93c35a,
  title = {Precambrian basement map of the northern midcontinent, U.S.A.},
  author = {P. K. Sims},
  year = {1990},
  doi = {10.3133/i1853a},
  url = {https://pubs.usgs.gov/publication/i1853A},
  note = {Source identifier: i1853A}
}