There's a book of interviews with Oliver Stone, translated and transcribed - the interviews are pretty recent, so it's an interesting enough read. It's kind of a funny set of interviews because Putin's clearly to the right of Oliver Stone in many ways, but to the left of him (or I guess I should say to the Soviet of him, not sure it is leftism exactly) in others, and reading their navigation of these fundamental misunderstandings is interesting. https://www.amazon.c...s/dp/1510733426
It's a pretty easy read because it's a transcription of interviews that were meant for public consumption anyway.
Now, for more serious material: if he's interested in current events, books might be too behind the times (although they would of course provide an important background). You could look through some of these links for what is currently going on - as a caution, they're hosted on 4chan, which has no filters or moderation for profanity or anything that is not strictly illegal, so while the links are clean, some of the comments might not be particularly heartwarming:
Especially the second set of links is relevant.
To understand Putin and modern Russia, esp. as it relates to the US, you have to understand the geopolitics of where Russia is currently exerting influence - so while Ukraine and etc. are important, the middle east is currently at a crisis point and Russia is intimately involved with some of the players there.
Finally, I don't say this to be politically controversial, but to get a grasp of the full implications of Putin's plans for Russia, you've got to consider seriously what his play is in the US with Trump.