Metrological features of the rubidium two-photon standards of the BNM-LPTF and Kastler Brossel LaboratoriesL. Hilico, R. Felder, D. Touahri, O. Acef, A. Clairon and F. BirabenEur. Phys. J. AP, 4 2 (1998) 219-225DOI: https://doi.org/10.1051/epjap:1998263