@misc{indiciaef88b76f25867,
  title = {Intensity correlations in optical nonlinear processes by photon counting techniques},
  author = {Davidson, F. and Klebba, J. and Tittel, F.},
  year = {1970},
  url = {https://ntrs.nasa.gov/citations/19700056487},
  note = {Source identifier: 19700056487}
}