Physical Constants and Metrology https://cms.gutow.uwosh.edu/Gutow/useful-chemistry-links/physical-constants-and-metrology https://cms.gutow.uwosh.edu/Gutow/@@site-logo/DrGlogo2.png Physical Constants and Metrology Fundamental Physical Constants (NIST) SI Units (BIPM) Guide to the Expression of Uncertainty in Measurement (the GUM from BIPM)