@misc{indiciaef4bd344782e6,
  title = {20th century U.S. mineral prices decline in constant dollars},
  author = {Daniel E. Sullivan and John L. Sznopek and Lorie A. Wagner},
  year = {2000},
  doi = {10.3133/ofr00389},
  url = {https://pubs.usgs.gov/publication/ofr00389},
  note = {Source identifier: ofr00389}
}