@misc{indiciae4dae8ee2132d,
  title = {Chronic daily headache.},
  author = {V Pfaffenrath and H Isler and K Ekbom},
  year = {1993},
  doi = {10.1177/0333102493013s1214},
  url = {https://pubmed.ncbi.nlm.nih.gov/8500152/},
  note = {Source identifier: 8500152}
}