I do not exaggerate too much, but many book can makes a house collapsed.
It is possible that many books will have a lot of weight that one has a chance to make the house collapsed.
Often designed to get the weight 150 kg per square meter, but the book may be hard to 500-1000 kg per square meter, which is not good for the house.
You should be prepared to take the first letter in the corner of the house. And make it home in a stronger than usual. Or a letter placing it near the spot where the beam receiver. It is better to be in the middle of the room.
