There are many books to learn Norwegian for grown-ups.  Most of them come in two parts: "Tekstbok" (text book) and "arbeidsbok" (exercise book).

They all cover, more or less, the same topics about Norway, such as everyday life, job, school etc, which are thought to be essential for taking a competence test. On A1-A2 level (nivå) they make an introduction to these subjects, while on B1-B2 level, a more detailed approach is made.

Most of the books can be bought either on paperback or as e-books. Also on the official sites there are extras, such as videos and exercises. Here are links to the most common books on the starting level but most of them have a series to higher levels (B1-B2):