@misc{indiciae172185f41003,
  title = {Echocardiogram in calcified mitral anulus.},
  author = {D S Hirschfeld and B B Emilson},
  year = {1975},
  doi = {10.1016/0002-9149(75)90489-0},
  url = {https://pubmed.ncbi.nlm.nih.gov/1166841/},
  note = {Source identifier: 1166841}
}