@misc{indiciae5fd32ceccc8b,
  title = {The determination of calcium in phosphate, carbonate, and silicate rocks by flame photometer},
  author = {Henry Kramer},
  year = {1956},
  doi = {10.3133/tei623},
  url = {https://pubs.usgs.gov/publication/tei623},
  note = {Source identifier: tei623}
}