This 50th Edition, published August 2008, is a special edition and contains ALL of the yarns and yarn companies from the time this publication was created.  There are more than 13000 yarns listed from more than 300 resources.

Valuable Knitting Information is a practical and easy-to-use source book of yarn interchange data. This book has a HUGE abount of yarn information.

This is the most extensive base edition and, according to the publisher, may be the last edition to be produced!

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.