Physical constants, units and conversion
the NIST Reference
on Constants, Units, and Uncertainty
Fundamental
Physical Constants - Non-SI units 1998;
CODATA recommended
2002
Units on
the Web - selection of links at the Uni of Geneve
The
Versatile Units Converter at the Universite de Geneve
Conversion of Units (at Inst. of Chemistry, FU Berlin)
The Conversion
factors for energy equivalents at NIST
Unit
Systems in Electromagnetism (Dept. of Electronic Engineering,
University of Surrey)