@conference{206896,
  author = {Tara Fortier and Neil Ashby and James Bergquist and Marie Delaney and Scott Diddams and Thomas Heavner and Leo Hollberg and Wayne Itano and Steven Jefferts and K Kim and Windell Oskay and Thomas Parker and Jon Shirley and Jason Stalnaker and Filippo Levi and Luca Lorini},
  title = {Improved Limits on Variation of the Fine Structure Constant and Violation of Local Position Invariance},
  year = {2007},
  month = {2007-05-29},
  publisher = {Proc. 2007 Joint Mtg. IEEE Intl. Freq. Cont. Symp. and EFTF Conf., Geneva, CH},
  url = {https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=50561},
  language = {en},
}