Cruze with variations and example
Enthusiastic Artist: How to draw triquetras by Margaret Bremner Certified Zentangle Artist
Celtic Knots - advanced by ~SecondGoddess on deviantART
Celtic knot-awesome, now it's not so terrifying to create:)
C ...... for Celtic knots
ArtCat86, via Flickr
Uncherys | Flickr - Photo Sharing!
IMG_0003 by ArtCat86, via Flickr Love this Flickr group of Freehand doodle patterns. So many ideas with step by step drawings