@misc{indiciae074484d84f30,
  title = {Letter: Heart sounds by echo.},
  author = {A A Luisada and E Craige},
  year = {1976},
  doi = {10.1161/01.cir.54.3.526},
  url = {https://pubmed.ncbi.nlm.nih.gov/947588/},
  note = {Source identifier: 947588}
}