Roman Pichler published a small but brilliant practical book focusing on agile Product Management with Scrum. Of course, it is focusing on the Product Owner's tasks. This is a welcome counter weight to the predominant developer and Scrum Master focused literature out there on the Scrum market.
Instead of reviewing it and repeating myself here, I simply link to the amazon product pages including my reviews in German and English.
There are lots of books out there where the author just offers a looong list of options, still leaving a confused reader. Not so with this book.
It really is a small, focused and focused book worth every cent. There is another good book out there on product management, which I find to be too general. If you are living in an agile environment, this is your choice!