That's because you shouldn't glue heavy loads to paper!
Common sense tell you NOTHING?!

Try using screws like normal people!
( Methylene Blue - electrohead, Tue 27 May 2008, 14:26, archived)

or brackets, to spread the weight too

( sleepybinky, Tue 27 May 2008, 14:27, archived)

Or nails.
No more no more nails glue.
( mike woz ere 7442200 & 7696970 getter, Tue 27 May 2008, 14:28, archived)

pffft
I'm envisaging a man getting hit on the head by a bookshelf.
It's quite funny.
( TY&GN, Tue 27 May 2008, 14:28, archived)

Yes
that happened too, and made me fall into a pile of other stuff which I was hoping to tidy away. I don't know if anything else was damaged but something certainly went crunch.
(Fles is a man amongst gods., Tue 27 May 2008, 14:34, archived)