@misc{indiciae5af783b8339d,
  title = {Optical frequency metrology.},
  author = {Th Udem and R Holzwarth and T W Hänsch},
  year = {2002},
  doi = {10.1038/416233a},
  url = {https://pubmed.ncbi.nlm.nih.gov/11894107/},
  note = {Source identifier: 11894107}
}