This is a compilation of materials from other sources, most of which are readily available to everyone but it's very convenient to have all the information in one place. However, some of the information is inaccurate, some of the illustrations are out of date, and many are poor copies of photocopies that aren't legible. I find this inexcusable in a book intended for designers and one that is $100+. Unfortunately, it is the only book of its kind. I recommend double checking any information that you take from it. Reznikoff is the only comparable book and that is even more out of date. At least Reznikoff was well produced though.