Names of Knots

Hello, I was just hoping some one might know of a site or book which explains how knots (e. g., the "true lover's knot", the "sheep-shank", the "granny knot") get their names. Thanks in advance for any information.

If you'll go to www.google.com/ and type in "knots," there are several sites like www.realknots.com/ knots/