This book is as advertised. It provided an excellent overview of a wide range of mathematical topics at a level suitable as an introduction to many areas. I some university level mathematics, but have not referred to it for a few decades now. The references given in many topics, especially those with comments, are also useful. I have not read all of it cover to cover, because it is a reference not a textbook. However, I came across the one article of Partial Differential Equations that provided an online link to a much larger version of the same article. Such a device would have been nice elsewhere. It would be one solution to the problem of trying to encompass all of mathematics in a single volume.