I use Syllabus 2019 and Glossary from the official ISTQB site. I found also some books, but those are quite old, like this one: Advanced Software Testing - Vol. 3, 2nd Edition: Guide to the ISTQB Advanced Certification as an Advanced Technical Test Analyst 2nd Edition, which was released in 2015.
I found also some question dumps, but don't know much about source and correctness. What kind of learning package or materials should I buy to prepare for this exam?