Hi Terje,
you can make hierarchies with the “/” inside the pages name, like [[book/chapter 1/subchapter 1]].
Example:
The page to chapter 1 and subchapter 1 then looks like this:
And the page to the book with all linked references and the hierarchy looks like this:
There you can find all the notes for all the levels of the hierarchy under linked references.
Hope this is, what you were searching for and helped 