"1.2 Normative References reads in part:

• • • • • 
          International System of Units (SI), NIST Reference, http://physics.nist.gov/cuu/Units/units.html.

That is a webpage and not a NIST Reference.

The NIST Reference, which partially appears on the webpage in reference is:

A. Thompson and B. N. Taylor, The NIST Guide for the use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition. http://www.nist.gov/pml/pubs/sp811/index.cfm"