@misc{indiciaeb32a120bccf5,
  title = {Grade-tonnage and other models for diamond kimberlite pipes},
  author = {J. D. Bliss},
  year = {1992},
  doi = {10.1007/bf01782275},
  url = {https://pubs.usgs.gov/publication/70016991},
  note = {Source identifier: 70016991}
}