Nelson, L.
, Levine, J.
and Hetzel, P.
(2000),
Comparing Primary Frequency Standards at NIST and PTB, 2000 IEEE Intl. Freq. Cont. Symp. , Kansas City, MO, USA, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=105491
(Accessed December 16, 2024)