@misc{1172971,
  author = {John L Prather},
  title = {Atomic energy levels in crystals:},
  year = {1961},
  month = {1961-01-01 05:01:00},
  publisher = {, National Institute of Standards and Technology, Gaithersburg, MD},
  doi = {https://doi.org/10.6028/NBS.MONO.19},
  language = {en},
}