@misc{indiciae107fdc016aff,
  title = {Secular variation in economic geology},
  author = {Richard J. Goldfarb and Dwight Bradley and David L Leach},
  year = {2010},
  doi = {10.2113/gsecongeo.105.3.459},
  url = {https://pubs.usgs.gov/publication/70230185},
  note = {Source identifier: 70230185}
}