My interest in Celtic Knots began when I read George Bain's book, 'Celtic Art The Methods of Construction', published by Constable, London,
ISBN 0 85335 196 1 (hardback) and 0 09 461830 5 (paperback).
I suspect it's no longer in print.
When I was doing pyrography, I concentrated mostly on Celtic Knots, and you can see some of my pyrographs by clicking on the menu. There are also a couple of animations, an alphabet, and some sections which can be joined to form more complicated knots.