@misc{indiciaeb369a27745c0,
  title = {Letter: Nitrous-oxide asphyxia.},
  author = {P J Helliwell},
  year = {1974},
  doi = {10.1016/s0140-6736(74)90659-x},
  url = {https://pubmed.ncbi.nlm.nih.gov/4136957/},
  note = {Source identifier: 4136957}
}