Writing an academic book review can be a daunting task, especially if you have to review multiply sources in the same paper. How do you even structure a paper that must compare and contrast multiple works at the same time? Here are some guidelines to make the process a little easier.
If the two books you are reviewing are two volumes of the same multi-volume set, you should treat them as one book unless there is a great deal of difference between the two. Otherwise, compare and contrast, but do not simply say what one book says and then say what the other books says. While you will need to summarize both books, you need to do more than that. Discuss how the books relate to your topic and what insights can be gained from them.
For example, I recently wrote a book review on the two volumes of Sir Ian Kershaw's biography of Hitler. Since most people know who Hitler was and what he did, it would make little sense to turn my book review of a biography of Hitler into a mini biography of Hitler. Instead, I focused on details that Kershaw provides that may be missing from other works as well as the process and sources he used. Most importantly, I showed how he gives insights into Hitler and the Third Reich in specific passages. For example, I gave examples of how Hitler's personality, as described by Kershaw, influenced policy in the Third Reich.
Again, do not simply summarize the content of the books. You need to be able to provide clear examples of how they shed light on your topic. If they offer very different views of the subject, explain why you think that may be. Is one of them right or is it just a matter or perspective? For example, you could right an article comparing Kershaw's biography with a memoir from someone who survived the Third Reich. Obviously, someone in a concentration camp has a much different perspective than someone writing a biography of Hitler many years later. On the other hand, the difference could be structural. For example, a textbook is not going to provide the level of detail that a biography can. It's focus is much to broad for that.
You must also identify what the authors are trying to say about their subject. Then you must state whether you agree or not and why.
Here are some good websites you examples you can use as a guide to get you started. Just remember that the structure of your book review is secondary to the truths you can pull from the book. Do not be afraid to offer your own thesis to the issues discussed in the books. Just remember that you need to use the books to help support your claims.