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. 1988 Apr 1;93(2):85–144. doi: 10.6028/jres.093.010

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The Journal of Research of the National Bureau of Standards is a publication of the U.S. Government. The papers are in the public domain and are not subject to copyright in the United States. Articles from J Res may contain photographs or illustrations copyrighted by other commercial organizations or individuals that may not be used without obtaining prior approval from the holder of the copyright.

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Recent values of R. The values from Cohen and Taylor [1] are adjustments. The value from Colclough et al. [13] was obtained with a cylindrical acoustic resonator.