The Encyclopedia is a reference for how to identify quilt blocks. In the intro to the book, author Barbara Brackman explains that she used 20th century magazines and articles, mainly between 1920 and 1950, and mostly from the midwest, to attempt to put a name with a block and when it was first published. This book is the result of all her research. It is organized like an encyclopedia and a great way to figure out the name of a block.