As a new user, its unclear how to link books to a work (The answer is ofcourse filling in the 'Work' field when you add a physical book) However I think the 'Work' page should be clearly de-lineated from a book page.
Perhaps even change the aesthetic or have a banner that is a different colour explaining the function of a work and that users are able to add different books to it.
Providing a link to 'Add a Book to this Work' which pre-fills the work information into the book submission page would be great.
Thanks for the suggestion, clashpalace. I love this idea. We'll take this into consideration going forward.