Would you recommend some great book about Grunfeld defense?


Magnus has also used the Grünfeld from time to time, though he hasn’t played as much of it lately.
Peter Svidler is considered to be one of the best Grünfeld experts in the world and he still plays it regularly. Unfortunately quite many top-level opponents use anti-Grünfeld lines against him.
Rowson's book is a good starting point, an alternative could be Aagaard's Starting out: the Grünfeld. I have Dembo's book, which is a good repertoire book for black (though does not discuss many of the mainlines, where theory can be very deep), it is slightly outdated (but outside master level works fine) and you need to understand the basics before using it.
The "Starting out"-series might be worth a look. You get to know all the plans and ideas instead of just memorizing lines you don't understand from Svidler (who is, of course, one of the greatest experts in the Grünfeld). There are, by the way, free Short & Sweet courses available on chessable. Maybe you could check those out as well, but I'd still recommend the Starting out books.

Starting Out: The Grunfeld by Jacob Aagaard.....does a good job of teaching this opening.....
https://www.amazon.com/Starting-Out-Grunfeld-Defence-Everyman/dp/1857443500/ref=sr_1_1?keywords=Starting+Out%3A+The+Grunfeld+by+Jacob+Aagaard&qid=1663156097&s=books&sr=1-1
@1
The best book is... a data base.
'The Grünfeld is now a different opening from a few years ago' - MVL
A book is obsolete while being printed.
Study the games of MVL and Svidler and others.

If you have a lot of time, perhaps read the Grandmaster Repertoire book on the Grunfeld. I've read one on the Semi-Slav and even though I never go through most of the lines in a real game, it does a great job explaining the opening in depth which despite great things I've heard over the Chessables course, they skip a lot of details. Of course, use an engine while reading the book because there will be some improvements from the newest engines