@misc{indiciaef23a6bf1fd6d,
  title = {Bifocal glasses. Optical principles and defects.},
  author = {M el-Arabi and O Rashed},
  year = {1971},
  url = {https://pubmed.ncbi.nlm.nih.gov/5154719/},
  note = {Source identifier: 5154719}
}