@misc{indiciae50d63c495225,
  title = {The Penokee iron-bearing series of Michigan and Wisconsin},
  author = {Roland Duer Irving and Charles Richard Van Hise},
  year = {1892},
  doi = {10.3133/m19},
  url = {https://pubs.usgs.gov/publication/m19},
  note = {Source identifier: m19}
}