@misc{indiciae4ff1497eb6ff,
  title = {[Progress in eyeglass optics].},
  author = {W Köppen},
  year = {1995},
  doi = {10.1055/s-2008-1035358},
  url = {https://pubmed.ncbi.nlm.nih.gov/7474774/},
  note = {Source identifier: 7474774}
}