Acoustic Material Tables
   Extensive table of acoustic properties, expanded from the late Alan Selfridge's 1985 paper.
   http://www.ondacorp.com/tecref_acoustictable.html

Acoustic material property tables
   Specialty Engineering Associates
   http://www.ultrasonic.com/tables/index.htm

Seawater Sound Speed Calculator
   by Simon Richards.
   http://freespace.virgin.net/sd.richards/speed.html

Velocity of sound in some Biological Material
   Ultrasound physics. Parameters. Differences between X-rays and ultrasound.( Gonzalo Diaz M. M.D.)
   http://www.drgdiaz.com/tables.shtml#Velocity