@misc{indiciae4b82dd95089b,
  title = {Change of the isotopic abundance ratio within a sphere due to diffusion},
  author = {J.T. Bracken and F. E. Senftle},
  year = {1954},
  doi = {10.1063/1.1721618},
  url = {https://pubs.usgs.gov/publication/70221435},
  note = {Source identifier: 70221435}
}