On some levels, you will see Bookshelves with blue books. Such books are also level goals, and the task is to collect them from shelves.

The first match or booster activation you make next to a Bookshelf blows up its doors. After that, each following match or booster activation takes out one book from the shelf, and the books get counted towards the goal 📚

When the last book is taken from the Bookshelf, the Bookshelf itself gets destroyed.