@misc{indiciaefb5946e76283,
  title = {Geologic map of the Thebes quadrangle, Illinois and Missouri},
  author = {Richard W. Harrison},
  year = {1999},
  doi = {10.3133/gq1779},
  url = {https://pubs.usgs.gov/publication/gq1779},
  note = {Source identifier: gq1779}
}