I used these two books along with an online learning portal, initially famous for its Linux courses, as the primary study materials. I ordered the book on 8/31 and provisionally passed the exam on 10/3.
The study book is a quick read and does not contain superfluous content. I went through it quickly, and then a few days prior to the real exam, skimmed through again. The chapter reviews are easier than the companion practice tests, so you should get the set. I tended to score 95%+ on chapter reviews but 80% on the practice tests. For the questions I failed, I went through each and learned why I failed.
For full disclosure, I also have two AWS, six Azure and CISSP/CSSLP certifications, along with working in the cloud. This other experience needs to be counted towards my passing and I don't mean to imply in any way that getting this set of books is all one needs should someone not have additional training/experience. This is not a full cloud security training program and is not represented by the author as such.
For me, the 21 hour online course and these two books were what I used to pass the exam, along with my experience.