@misc{indiciae9d8a6619aa3d,
  title = {Unknown lip-flap procedures by Stein.},
  author = {N C Petersen},
  year = {1973},
  doi = {10.3109/02844317309056413},
  url = {https://pubmed.ncbi.nlm.nih.gov/4592850/},
  note = {Source identifier: 4592850}
}