@misc{indiciaed4c103eb8a48,
  title = {Change of the isotopic abundance ratio within a sphere due to diffusion},
  author = {Jim T. Bracken and F. E. Senftle},
  year = {1953},
  doi = {10.3133/tei402},
  url = {https://pubs.usgs.gov/publication/tei402},
  note = {Source identifier: tei402}
}