@misc{indiciae11b4876ce068,
  title = {Mining claim activity on federal land in the contiguous United States, 1976 through 2004},
  author = {J. Douglas Causey and David G. Frank},
  year = {2006},
  doi = {10.3133/ds228},
  url = {https://pubs.usgs.gov/publication/ds228},
  note = {Source identifier: ds228}
}