Hello @TheSwedishLord,
We don’t yet have materials which are grouped together as a book.
I would highly recommend you to go through our getting started series.
You could potentially consider each episode of the series as a chapter in a book 
Here are the links of the text and video form at of the episodes / chapters 
-
https://blog.dgraph.io/post/tutorial-1-getting-started/
https://youtu.be/u73ovhDCPQQ -
https://blog.dgraph.io/post/tutorial-2-getting-started/
https://youtu.be/8TKD-FFBVgE -
https://blog.dgraph.io/post/tutorial-3-getting-started/
https://youtu.be/f401or0hg5E
Every Wednesday we’ll have a new material coming out, so please subscribe to our youtube channel, the blog and may be even follow us on twitter @dgraphlabs 