@misc{indiciaea5df210f2e15,
  title = {Office endoscopy--when, why, what, and how.},
  author = {R O Gustafson and E B Kern},
  year = {1989},
  url = {https://pubmed.ncbi.nlm.nih.gov/2771412/},
  note = {Source identifier: 2771412}
}