@misc{indiciaefc90faaa8d4f,
  title = {Quality assurance manual for the Branch of Geochemistry, U.S. Geological Survey},
  year = {1990},
  doi = {10.3133/ofr90668},
  url = {https://pubs.usgs.gov/publication/ofr90668},
  note = {Source identifier: ofr90668}
}