@misc{indiciae543ca3e1a0bd,
  title = {Calculation of 230ThU isochrons, ages, and errors},
  author = {K.R. Ludwig and D.M. Titterington},
  year = {1994},
  doi = {10.1016/0016-7037(94)90229-1},
  url = {https://pubs.usgs.gov/publication/70017618},
  note = {Source identifier: 70017618}
}