El terme 'relativa incertesa estàndard' s'explica pel NIST al seu lloc web: «Standard Uncertainty and Relative Standard Uncertainty». The NIST Reference on constants, units, and uncertainties: Fundamental physical constants. NIST. [Consulta: 19 desembre 2011].
nist.gov
A more detailed listing of errors can be found in Beers, John S; Penzes, William B. «§4 Re-evaluation of measurement errors» (PDF). NIST length scale interferometer measurement assurance; NIST document NISTIR 4998 p. 9 ff, 01-12-1992. [Consulta: 17 desembre 2011].
«§VI: Uncertainty and range of validity». Engineering metrology toolbox: Refractive index of air calculator. NIST, 23-09-2010. [Consulta: 16 desembre 2011].
noaa.gov
ngs.noaa.gov
Astin & Karo 1959 Astin, A. V. & Karo, H. Arnold, (1959), Refinement of values for the yard and the pound, Washington DC: National Bureau of Standards, republished on National Geodetic Survey web site and the Federal Register (Doc. 59-5442, Filed, 30 June 1959, 8:45 a.m.)