@misc{indiciae8e8db05ed30f,
  title = {Geologic map and sections, Burt mica mine, Custer County, South Dakota},
  author = {John Wagstaff Adams},
  year = {1949},
  doi = {10.3133/ofr4918},
  url = {https://pubs.usgs.gov/publication/ofr4918},
  note = {Source identifier: ofr4918}
}