@misc{indiciaee7896bffee9a,
  title = {Sum and difference frequency generation in a two-level system with permanent dipole moments.},
  author = {R Bavli and YB Band},
  year = {1991},
  doi = {10.1103/physreva.43.5044},
  url = {https://pubmed.ncbi.nlm.nih.gov/9905624/},
  note = {Source identifier: 9905624}
}