As the "Revalidation exam" is a flight test then you should be familiar with what you are expected to demonstrate. You can download the
Examiners Schedule and then make sure that you are familiar with the exercises involved rather than reading all the books. You will have to do some navigation at the examiners discretion so be prepared for that, it may not be very formal but he will want to see you are competent and you have an up to date map. Be familiar with the check list and know how to complete the weight and balance and take off calculations. Most of it will be practical so there really isn't too much else you can study in the way of literature. Are you happy you can master the test without a practice, most instructors will be happy to take you through the test profile.