TY  - RPRT
TI  - Density matrix and entropies for electromagnetic fields.
AU  - IA Levín
AU  - D Otero
AU  - AN Proto
PY  - 1989
DO  - 10.1103/physreva.40.5998
UR  - https://pubmed.ncbi.nlm.nih.gov/9901977/
ID  - 9901977
ER  -