@misc{indiciaef17fa9c2ba8f,
  title = {Sample size preconcentration requirements for meaningful analysis of gold},
  author = {H. Edward Clifton},
  year = {1967},
  doi = {10.3133/ofr6748},
  url = {https://pubs.usgs.gov/publication/ofr6748},
  note = {Source identifier: ofr6748}
}