what book to refer to cover CISSP new topics. As of now i am studying official study guide 8th edition. Please reply
There are always change of domain (add or remove topic) and the official study guide will not able to catch up the changes.
https://www.isc2.org/-/media/ISC2/Certifications/Domain-Refresh/CISSP-Domain-Refresh.ashx
But honestly the official study guide still form the bases for your study and very good reference for you to start your study or exam prep.
I would suggest you look into the domain changes. Highlight the new /change one and try to see if you already have knowledge on those. I am sure the new ones are very common which you can find related knowledge easily.
Good luck.