Best policy would to have all non-fiction, or certainly books from academic publishers, with the page number facility for citation. This or a change to citing practice. I have resorted to putting KL before a reference as in Kindle Reference so KL 2734 for example. I don't suppose this helps unless the tutor or examiner knows the exact font size, spacing and layout, but at least it shows I am trying to demonstrate the provenance of my source. They could simply do a search for the phrase within the book, if verifying the quote, fact or figure is required, but that of course requires them to own the book in Kindle form.