@misc{indiciae594fc3039a9d,
  title = {Hypervirial Theorems and the Hellman- Feynman Theorem in Different Coordinate Systems},
  author = {Epstein, S. T.},
  year = {1965},
  url = {https://ntrs.nasa.gov/citations/19660006007},
  note = {Source identifier: 19660006007}
}