@misc{indiciaeb5c907477ae4,
  title = {Low-dose progestogens and ectopic pregnancy.},
  author = {P Liukko and R Erkkola},
  year = {1976},
  doi = {10.1136/bmj.2.6046.1257-a},
  url = {https://pubmed.ncbi.nlm.nih.gov/990873/},
  note = {Source identifier: 990873}
}