@misc{indiciae35dc006b2d54,
  title = {Letter: Estimating collateral circulation.},
  author = {D C Levin},
  year = {1975},
  doi = {10.1161/01.cir.51.2.397},
  url = {https://pubmed.ncbi.nlm.nih.gov/1112023/},
  note = {Source identifier: 1112023}
}