Flip Book Access

I have only just become aware of the huge number of books very easily
accessible in PDF, Text, and "flipbook" at Web Archive

Just look what turns up on these searches:

Byzantine

Mediaeval

Amazing, eh?

And even if the texts are old, many of them contain really nifty out
of copyright images and photographs just calling out to be used in
PowerPoints.

Plus, since the texts are searchable, it's a useful place to track
down plagiarism.