@misc{indiciaefec021e5edb4,
  title = {A simple device measuring differences in level in the oesophagus.},
  author = {P Ask and L Tibbling},
  doi = {10.3109/00016487809111938},
  url = {https://pubmed.ncbi.nlm.nih.gov/636876/},
  note = {Source identifier: 636876}
}