Ultracold strontium clock: Applications to the measurement of fundamental constant variationsA. D. Ludlow, S. Blatt, T. Zelevinsky, G. K. Campbell, M. J. Martin, J. W. Thomsen, M. M. Boyd and J. YeEur. Phys. J. Special Topics, 163 (2008) 9-18DOI: https://doi.org/10.1140/epjst/e2008-00806-8