@misc{indiciae2148c17ea229,
  title = {Energy-level calculation through perturbation theory.},
  author = {B Rath},
  year = {1990},
  doi = {10.1103/physreva.42.2520},
  url = {https://pubmed.ncbi.nlm.nih.gov/9904317/},
  note = {Source identifier: 9904317}
}