@misc{indiciae2082066ec68a,
  title = {Group sequential methods.},
  author = {D R Jones and J Whitehead},
  year = {1979},
  doi = {10.1038/bjc.1979.156},
  url = {https://pubmed.ncbi.nlm.nih.gov/475959/},
  note = {Source identifier: 475959}
}