@misc{indiciae89f5e45c8002,
  title = {Aging effects on heart rate variation.},
  author = {J B Schwartz and W J Gibb and T Tran},
  year = {1991},
  doi = {10.1093/geronj/46.3.m99},
  url = {https://pubmed.ncbi.nlm.nih.gov/2030273/},
  note = {Source identifier: 2030273}
}