@misc{indiciae97a76b017e74,
  title = {Bedrock geology of the Porcupine Mountains, Michigan},
  author = {Harold A. Hubbard},
  year = {1974},
  doi = {10.3133/ofr741052},
  url = {https://pubs.usgs.gov/publication/ofr741052},
  note = {Source identifier: ofr741052}
}