@misc{indiciae1e46bd386858,
  title = {Challenging or difficult headache patients.},
  author = {Stephen H Landy},
  year = {2004},
  doi = {10.1016/j.pop.2004.02.013},
  url = {https://pubmed.ncbi.nlm.nih.gov/15172517/},
  note = {Source identifier: 15172517}
}