The inadequacy of heterografts for mitral valve replacement.

@article{Geldof1971TheIO,
  title={The inadequacy of heterografts for mitral valve replacement.},
  author={W C Geldof and A. Kroon and A G Brom},
  journal={The Annals of thoracic surgery},
  year={1971},
  volume={11 4},
  pages={343-7}
}