The International System of Units (SI), 1991 (NIST Special Publication)

 "This booklet is the United States edition of the English translation of the sixth edition of 'Le Systeme International d'Unites (SI)', the definitive publication in the French language issued in 1991 by the International Bureau of Weights and Measures (BIPM)." Translation approved by the International Bureau of Weights and Measures. Includes appendixes on: Decisions of the CGPM and the CIPM; Practical Realization of the Definitions of Some Important Units; and the BIPM and the Meter Convention.