@misc{indiciaeed388662cc7b,
  title = {Historical statistics for copper in the United States, 1870-1978},
  author = {Margaret Slade},
  year = {1979},
  doi = {10.3133/ofr791697},
  url = {https://pubs.usgs.gov/publication/ofr791697},
  note = {Source identifier: ofr791697}
}