@misc{indiciae5d381bab2aeb,
  title = {Detailed geologic map of the recently active copper mines; Houghton and Keweenaw Counties, Michigan},
  author = {H. R. Cornwall and J.J. Runner and A. A. Stromquist and R. W. Swanson and W. S. White},
  year = {1949},
  doi = {10.3133/ofr504},
  url = {https://pubs.usgs.gov/publication/ofr504},
  note = {Source identifier: ofr504}
}