@misc{indiciaef438577a3a05,
  title = {Inexpensive electrophysiologic calibration unit.},
  author = {E G Duffin and L E Solberg and W G Hamilton and D H Singer},
  year = {1974},
  doi = {10.1109/tbme.1974.324393},
  url = {https://pubmed.ncbi.nlm.nih.gov/4852418/},
  note = {Source identifier: 4852418}
}