TY  - RPRT
TI  - Sum and difference frequency generation in a two-level system with permanent dipole moments.
AU  - R Bavli
AU  - YB Band
PY  - 1991
DO  - 10.1103/physreva.43.5044
UR  - https://pubmed.ncbi.nlm.nih.gov/9905624/
ID  - 9905624
ER  -