@misc{indiciae82699419fcd3,
  title = {Cyclic changes in cervical mucus, and its practical importance.},
  author = {A F Guttmacher and L B Shettles},
  year = {1940},
  url = {https://pubmed.ncbi.nlm.nih.gov/12305580/},
  note = {Source identifier: 12305580}
}