@misc{indiciae63681a6b7e05,
  title = {A service for problem families.},
  author = {L Polnay},
  year = {1985},
  doi = {10.1136/adc.60.9.887},
  url = {https://pubmed.ncbi.nlm.nih.gov/4051549/},
  note = {Source identifier: 4051549}
}