@misc{indiciae72309c109b07,
  title = {Factors controlling sulfur concentrations in volcanic apatite},
  author = {G. Peng and J.F. Luhr and J. J. McGee},
  year = {1997},
  url = {https://pubs.usgs.gov/publication/70019540},
  note = {Source identifier: 70019540}
}