@misc{indiciae81aff94b5c7e,
  title = {Long-term adequacy of metal resources},
  author = {D.A. Singer},
  year = {1977},
  doi = {10.1016/0301-4207(77)90036-8},
  url = {https://pubs.usgs.gov/publication/70009885},
  note = {Source identifier: 70009885}
}