On Mon, Feb 02, 2004 at 11:17:27AM +0100, Soren S. Jorvang wrote:
> You are probably right, but can you point me to an authoritative
> reference?

I guess this is fairly authoritative:
http://physics.nist.gov/cuu/Units/kelvin.html

The site seems to be down right now, but Google has it cached:
http://216.239.39.104/search?q=cache:qtHIKyrbZfYJ:physics.nist.gov/cuu/Units/kelvin.html

Less authoritative, but with more explanation, is:
http://antoine.frostburg.edu/chem/senese/101/measurement/faq/why-273.15-kelvin.shtml