@misc{indiciae8253140c4e0b,
  title = {Nonlinear optics with less than one photon.},
  author = {K J Resch and J S Lundeen and A M Steinberg},
  year = {2001},
  doi = {10.1103/physrevlett.87.123603},
  url = {https://pubmed.ncbi.nlm.nih.gov/11580512/},
  note = {Source identifier: 11580512}
}