@misc{indiciae6c3932bb22ec,
  title = {A variational principle in optics.},
  author = {Jacob Rubinstein and Gershon Wolansky},
  year = {2004},
  doi = {10.1364/josaa.21.002164},
  url = {https://pubmed.ncbi.nlm.nih.gov/15535374/},
  note = {Source identifier: 15535374}
}