Valuable Knitting Information, 49th Edition for Spring 2008, is a practical and easy-to-use source book of yarn interchange data. This book has a HUGE abount of yarn information.

Split into three major sections: general information about fibers, yarn interchange guidelines, and knitting terms and techniques; specific yarn information, listed by manufacturer; and an alphabetical list of all of the yarns.

See also the new 50th Edition, which is a new base edition!