Twenty years ago, when I started as a jury for undergraduate work and research projects, I introduced as a work rule the arching of sources, placing the burden of proof in which he offers the appointment; that is, who cited should show me in physical ( book or photocopy) the page where the appointment appeared.
Now, I have incorporated the possibility of indicating the digital signature of the book (through the use of the international registration, ISBN and Issue Date).
It is part of the rules that accept both my tutors and those who undergo my evaluation as a jury.
This last alternative could be a tool to walk forward in the case of plagiarism, through prior control.