@article{104316,
  author = {Neil Ashby and Thomas Heavner and Steven Jefferts and Thomas Parker and A Radnaev and Y Dudin},
  title = {Testing local position invariance with four Cesium fountain primary frequency standards and four NIST Hydrogen masers},
  year = {2007},
  number = {98},
  month = {2007-02-16},
  publisher = {Physical Review Letters},
  url = {https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=50482},
  language = {en},
}