@misc{indiciae79e4c6bc6770,
  title = {Nonparoxysmal bidirectional rhythm.},
  author = {M C Proper and N T Ditchek and A D Purcell and M H Smith},
  year = {1971},
  doi = {10.1378/chest.59.3.333},
  url = {https://pubmed.ncbi.nlm.nih.gov/5544976/},
  note = {Source identifier: 5544976}
}