@misc{indiciaef752b7756a91,
  title = {Geology and mineral resources of the Hardin and Brussels quadrangles (in Illinois)},
  author = {William W. Rubey},
  year = {1952},
  doi = {10.3133/pp218},
  url = {https://pubs.usgs.gov/publication/pp218},
  note = {Source identifier: pp218}
}