@misc{indiciae192d801185f9,
  title = {Geologic map of the Ponca quadrangle, Newton, Boone, and Carroll Counties, Arkansas},
  author = {Mark R. Hudson and Kyle E. Murray},
  year = {2003},
  doi = {10.3133/mf2412},
  url = {https://pubs.usgs.gov/publication/mf2412},
  note = {Source identifier: mf2412}
}