@misc{indiciaeacb6bad5324b,
  title = {Hypervirial theorems and the hellmann- feynman theorem in different coordinate systems.},
  author = {Epstein, S. T.},
  year = {1965},
  url = {https://ntrs.nasa.gov/citations/19650054142},
  note = {Source identifier: 19650054142}
}