@misc{indiciaeca33e1cc7504,
  title = {Geologic map of the Sixteen Quadrangle, Gallatin and Meagher counties, Montana},
  author = {L.W. McGrew},
  year = {1974},
  doi = {10.3133/ofr74108},
  url = {https://pubs.usgs.gov/publication/ofr74108},
  note = {Source identifier: ofr74108}
}