@misc{indiciaef427d0921fdc,
  title = {Lambert diffuse reflection from general quadric surfaces.},
  author = {K W Brand and F A Spagnolo},
  year = {1967},
  doi = {10.1364/josa.57.000452},
  url = {https://pubmed.ncbi.nlm.nih.gov/6027820/},
  note = {Source identifier: 6027820}
}