@misc{indiciae5a8d4db52190,
  title = {Method and apparatus for measuring frequency and phase difference},
  author = {Kobayashi, Herbert S. and Lichtenberg, Christopher L. and Shores, Paul W. and Cunningham, Allen R.},
  year = {1989},
  url = {https://ntrs.nasa.gov/citations/20080012361},
  note = {Source identifier: 20080012361}
}