@misc{indiciaecc2436cfe80d,
  title = {Letter: Upper gastrointestinal endoscopy.},
  author = {P M Smith},
  year = {1974},
  doi = {10.1016/s0140-6736(74)91392-0},
  url = {https://pubmed.ncbi.nlm.nih.gov/4134445/},
  note = {Source identifier: 4134445}
}