@misc{indiciae20731cbe8f17,
  title = {Hydrogen Maser Clock (HMC) Experiment},
  author = {Vessot, Robert F. C. and Mattison, Edward M.},
  year = {1997},
  url = {https://ntrs.nasa.gov/citations/19970028997},
  note = {Source identifier: 19970028997}
}