"Unity in action" I here took, norms:
https://books.google.com/books?id=XWx9DwAAQBAJ
Don't know if yet, other books on unity, since the book allows you to make first steps to become familiar with the package, and then practice, experimentation, reading documentation, analysis of finished projects, etc.
Another thing is C#, to learn it, too, but I'm not familiar with the books in this direction.