@misc{indiciae93efc478d17b,
  title = {Upright exercise echocardiography.},
  author = {K W Amon and M H Crawford},
  year = {1979},
  doi = {10.1002/jcu.1870070510},
  url = {https://pubmed.ncbi.nlm.nih.gov/114544/},
  note = {Source identifier: 114544}
}