@misc{indiciaeb6c1511b1597,
  title = {Heartrate calculator.},
  author = {R J Trudnowski},
  year = {1973},
  doi = {10.1007/bf03026223},
  url = {https://pubmed.ncbi.nlm.nih.gov/4718361/},
  note = {Source identifier: 4718361}
}