According to Bruce Schneier's blog, his book _Data and Goliath_, when read on Kindle, reaches the end of the main text when the Kindle app (or device) says you're 44% of the way through. Basically, there's more raw text in the form of citations and references than in the main body of the book.
What amuses me about this observation, however, is that 44% means the "main text" is not the "majority content", and you could make a point that what Schneier has done is to gather a very extensive list of relevant reference materials, then written a kind of index summary as an appendix.
Mokalus of Borg
PS - I haven't read the book yet, but it's on the list.
PPS - I have a very long and complex list.