First of all, you need to know what material and at what level you need to have information on each subject. There must be some guidelines for the exam.

Before you start, plan out the material to study. Perhaps even skim through each book to get an idea of what is there. Often books will have summaries at the end of each chapter. It is good to read those first, if possible.

The best way to study the three subjects is to spend about 55 minutes on one subject, and then take a 5-minute break where you get up, walk around and stretch, to get your blood flowing. Then switch to the next subject. Doing that will allow you to be alert in each subject.

I am sorry, but I can't recommend books, since it depends so much on the exam requirements.

Best wishes in doing well in your exams. I am sure you will be a champion