@misc{indiciae413fc18461a5,
  title = {Precise nonvariational calculations on the helium atom.},
  author = {MI Haftel and VB Mandelzweig},
  year = {1988},
  doi = {10.1103/physreva.38.5995},
  url = {https://pubmed.ncbi.nlm.nih.gov/9900353/},
  note = {Source identifier: 9900353}
}