@misc{indiciaea6c1ad26507d,
  title = {Stratigraphic framework and distribution of lignite in the Claiborne Group, Calhoun County, Arkansas},
  author = {B.S. Hackman},
  year = {1982},
  doi = {10.3133/ofr82787},
  url = {https://pubs.usgs.gov/publication/ofr82787},
  note = {Source identifier: ofr82787}
}