APPROVALS and STANDARDS

National metrological institutions: In Holland the NMI (Nederlands MeetInstituut), in Germany the PTB (Physikalisch-Technische Bundesanstalt), in the U.S. N.I.S.T. (Bureau of Standards) , in the U.K. the N.P.L. (National Physical Laboratory).
More links and addresses are to be found at the site of  B.I.P.M.