TY  - RPRT
TI  - 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.
AU  - Brown, R. T.
PY  - 1968
UR  - https://ntrs.nasa.gov/citations/19680056734
ID  - 19680056734
ER  -