@misc{indiciae20a9a51140fe,
  title = {Gravel deposits of the Caddo Gap and De Queen quadrangles, Arkansas},
  author = {Hugh D. Miser and Albert Homer Purdue},
  year = {1919},
  doi = {10.3133/b690b},
  url = {https://pubs.usgs.gov/publication/b690B},
  note = {Source identifier: b690B}
}