@misc{indiciae21c993718a4c,
  title = {Improved numerical control of oscillator frequency},
  author = {Cellier, A. and Huey, D. C. and Ma, L. N.},
  year = {1977},
  url = {https://ntrs.nasa.gov/citations/19770000347},
  note = {Source identifier: 19770000347}
}