@misc{indiciae5985efbe8e8d,
  title = {Controlling confounding when studying large pharmacoepidemiologic databases: a case study of the two-stage sampling design.},
  author = {J P Collet and D Schaubel and J Hanley and C Sharpe and J F Boivin},
  year = {1998},
  doi = {10.1097/00001648-199805000-00011},
  url = {https://pubmed.ncbi.nlm.nih.gov/9583424/},
  note = {Source identifier: 9583424}
}