@misc{indiciaeca054102e4d8,
  title = {GEOINDEX database on geologic maps accessible using GSSEARCH search and retrieval software},
  author = {H. Kit Fuller and Gregory B. Gunnells},
  year = {1991},
  doi = {10.3133/ofr91575a},
  url = {https://pubs.usgs.gov/publication/ofr91575A},
  note = {Source identifier: ofr91575A}
}