@misc{indiciae623abe35bd5d,
  title = {Retrograde cervical perforation by the copper-T device.},
  author = {K G Nygren and E D Johnasson},
  year = {1974},
  doi = {10.3109/00016347409157758},
  url = {https://pubmed.ncbi.nlm.nih.gov/4440469/},
  note = {Source identifier: 4440469}
}