@misc{indiciae423c15f703f1,
  title = {A German prothrombin time proficiency testing program.},
  author = {H Beeser and R Merten and H Drescher and J Fischer},
  year = {1975},
  url = {https://pubmed.ncbi.nlm.nih.gov/1138412/},
  note = {Source identifier: 1138412}
}