Recent improvements in NIST-F1 and a resulting accuracy of δf/f=0.61×10-15. - Thomas P. Heavner; Steven R. Jefferts; Elizabeth A. Donley; Jon H. Shirley; Thomas E. Parker (IEEE Trans. Instrum. Meas., 2005)

First-Order Sideband Pulling in Atomic Frequency Standards. - Jon H. Shirley; Thomas P. Heavner; Steven R. Jefferts (IEEE Trans. Instrum. Meas., 2009)