Geoffrey P. Barwood, Patrick Gill, Guilong Huang, Hugh A. Klein. Observation of a Sub-10-Hz Linewidth :::88:::Sr:::+ 2:::S::1/2::-:::2:::D::5/2:: Clock Transition at 674 nm. IEEE T. Instrumentation and Measurement, 56(2):226-229, 2007. [doi]
Abstract is missing.