@misc{1147441,
  author = {Gwen E Bennett},
  title = {NIST time and frequency bulletin no. 491:},
  year = {1998},
  month = {1998-01-01 05:01:00},
  publisher = {, National Institute of Standards and Technology, Gaithersburg, MD},
  doi = {https://doi.org/10.6028/NIST.IR.5071-10},
  language = {en},
}