TY  - RPRT
TI  - Perturbation theory in multireference spaces.
AU  - W Duch
AU  - GH Diercksen
PY  - 1992
DO  - 10.1103/physreva.46.95
UR  - https://pubmed.ncbi.nlm.nih.gov/9907839/
ID  - 9907839
ER  -