@misc{indiciaefd1aefdc409e,
  title = {Digital grade and tonnage data for 50 types of mineral deposits; Macintosh version},
  author = {Donald A. Singer and Dan L. Mosier and David W. Menzie},
  year = {1993},
  doi = {10.3133/ofr93280},
  url = {https://pubs.usgs.gov/publication/ofr93280},
  note = {Source identifier: ofr93280}
}