@misc{indiciaef35a6e4ae5a2,
  title = {A wide-range linear beat-by-beat cardiotachometer},
  author = {Caldwell, W. M. and Smith, L. D. and Wilson, M. F.},
  year = {1970},
  url = {https://ntrs.nasa.gov/citations/19710029545},
  note = {Source identifier: 19710029545}
}