Hi Charles. Thanks for the question. From my point of view one books is never enough no matter for what certification. I however think starting with Spring Quickly is a good point. I then also recommend you Spring in Action and Spring Security in Action. You should also read Spring Boot up and running by Mark Heckler.
But after all, you will find very useful to use some mock exams. Also on my YT channel you'll find some nice videos which are of course free youtube.com/c/laurentiuspilca