I picked up this book at a bookstore on a bit of a whim. I hadn't looked at it much when I purchased it but when I got home and dove in, I was very pleased!
The book is an alphabetical listing of styles and design movements from victorian to today (and maybe a few further back in time). The information written about each movement/style is concise but more than enough to give you a the context you need.
The articles are short enough that this book would be a great bathroom book for your studio or even just to read one-a-day. Keep it close to your desk cause it is a very accessible reference book. Looking up stuff on the fly is easy.
I think this is a must have for anyone who wants to be informed. By knowing about style, you can use styles smartly in graphic design and the stylings will actually function as content, augmenting the messages you're trying to communicate.