@misc{indiciae3a8345c2c8f5,
  title = {Who joins a PPO?},
  author = {P B Ginsburg and S D Hosek and M S Marquis},
  year = {1987},
  url = {https://pubmed.ncbi.nlm.nih.gov/10280665/},
  note = {Source identifier: 10280665}
}