Place books on trucks in an upright position with no other materials stacked on top of them. If a shelf of a truck is only partially full, keep books vertical with a book end or with a group of books laid flat to support the others.

Do not place books on their fore edges (the front edge of the text block) even for a short period of time -- as for example when arranging them in call number order -- since this can cause the body of a book to come loose from its covers.
The picture below shows an example of books placed on their fore edges. It is best NOT to do this:
