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.
eReader Referencing