@article{DA,
      url = {http://digitalcollections.ohsu.edu/record/6842},
      title = {Artificial heart valves},
      abstract = {Digital scan of a 35mm slide. Black-and-white comparison  of four ball-and-cage style artificial heart valves,  labeled A, B, C, and D. A and C have opaque plastic balls,  while B has a transparent plastic ball. D has a metal ball.  A has a plastic cage with a white mesh cloth-covered ring.  B, and C have metal cages with white mesh cloth-covered  rings. D has a metal cage entirely covered in white mesh  cloth.},
      number = {DA},
      doi = {https://doi.org/10.6083/M43F4N86},
      recid = {6842},
}