NIST Guide to the SI
= NIST Guide to the SI
{c}
https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8
Special Publication 811, Appendix B.8, conversion factors. Modern metric equivalents corroborate rounded values; they are distinguished from historical calibrations.