The Knitter's Book of Yarn - Clara Parkes

I love this book! It describes different types of fibers (protein, cellulose, cellulosic, and synthetic), their properties, and where they come from. It also covers yarn production (commercial and handmade), color, spin, and ply. There's at least one sample pattern for each single and multiple ply yarn as well as for felt and textured yarn. The list of resources with websites is great!