National Oceanographic and Atmospheric Agency, 1976. U.S.
Standard Atmosphere, 1976. NOAA-S/T 76-1562. (A PDF of this document may
be available at
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770009539_1977009539.pdf
or
http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA035728
although neither link has proven to be reliable.)