@misc{indiciaefd57851f23c0,
  title = {Tonography; technical difficulties and control studies.},
  author = {R W SPENCER and E D HELMICK and H G SCHEIE},
  year = {1955},
  url = {https://pubmed.ncbi.nlm.nih.gov/13257981/},
  note = {Source identifier: 13257981}
}