@misc{indiciaef8cddda6dfae,
  title = {Improved mitral valve replacement.},
  author = {A Bernhard and H H Sievers and U Nellesen and I Maurer},
  year = {1990},
  doi = {10.1016/1010-7940(90)90010-w},
  url = {https://pubmed.ncbi.nlm.nih.gov/2185800/},
  note = {Source identifier: 2185800}
}