@misc{indiciae0a08e84be1ba,
  title = {Application of grade and tonnage deposit models; the search for ore deposits possibly amenable to small-scale mining},
  author = {J. D. Bliss and G. E. McKelvey and M. S. Allen},
  year = {1990},
  doi = {10.3133/ofr90412},
  url = {https://pubs.usgs.gov/publication/ofr90412},
  note = {Source identifier: ofr90412}
}