This is definitely safe

The power of knowledge

Wait I want to read that one!
*building falls*

...but the compression strength of paper is actually higher than that of concrete...so actually it could hold more weight than the concrete! ...and to quote the post "Trust me, I'm an engineer" :)

But why would you do this to books?

"Trust me, I'm an engineer and those textbooks cost more than fixing it" my friends reaction to this post

What a waste of books

Strong foundation, remember that kids.