@misc{indiciaef81e84f3fa34,
  title = {Geologic map and recent drilling data of the Durango area, Dubuque County, Iowa},
  author = {Arthur Emerson Flint and C. Ervin Brown},
  year = {1954},
  doi = {10.3133/ofr5490},
  url = {https://pubs.usgs.gov/publication/ofr5490},
  note = {Source identifier: ofr5490}
}