@misc{indiciae7baafaa4d503,
  title = {Survival analysis in observational studies.},
  author = {K Bull and D J Spiegelhalter},
  year = {1997},
  doi = {10.1002/(sici)1097-0258(19970515)16:9<1041::aid-sim506>3.0.co;2-f},
  url = {https://pubmed.ncbi.nlm.nih.gov/9160498/},
  note = {Source identifier: 9160498}
}