@misc{indiciaed4147ada9e92,
  title = {Virial theorem, the variational principle, and nonlinear parameters in quantum mechanics - Application to the 3 super 1 D and 3 super 3 D states of the helium isoelectronic series.},
  author = {Brown, R. T.},
  year = {1968},
  url = {https://ntrs.nasa.gov/citations/19680056734},
  note = {Source identifier: 19680056734}
}