@misc{indiciae419eac7bd68c,
  title = {Automatic frequency discriminators and control for a phase-lock loop providing frequency preset capabilities Patent},
  author = {Kline, A. J., Jr. and Peterson, W. D.},
  year = {1969},
  url = {https://ntrs.nasa.gov/citations/19710009992},
  note = {Source identifier: 19710009992}
}