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BIPM SI Brochure, 9th edition, version updated 2026
Authoritative SI definitions, SI prefixes and accepted non-SI relationships.
https://www.bipm.org/en/publications/si-brochure

NIST Guide to the SI, Appendix B / Handbook 44
U.S. customary and non-SI conversion factors, exactness and rounding guidance.
https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors

NIST binary prefixes reference
Binary prefixes and the distinction between decimal and binary data units.
https://physics.nist.gov/cuu/Units/binary.html