How do you add a book chapter? There doesn't seem to be anywhere to do that. there's a book section but you can only enter one author, not the author of the chapter and the author of the book
You need to click on "Author" to have access to more: "Book Author", "Contributor", "Editor", "Series Editor" and "Translator". The sign "+" to the right of the field allows you to enter more authors.
Upgrade Storage
Edit: See the link provided below