@misc{indiciaec9e01c4229bf,
  title = {Geologic maps and sections of the Helen Beryl, Elkhorn, and Tin Mountain pegmatite mines, South Dakota},
  author = {Lincoln R. Page and Mortimer Hay Staatz and and others},
  year = {1955},
  doi = {10.3133/ofr55128},
  url = {https://pubs.usgs.gov/publication/ofr55128},
  note = {Source identifier: ofr55128}
}