How can I rename documents in iBook

I have tried to select 'Select' in iBook interface and click the file to edit the file name to new name. It works during the opening of ibook. But the true file name is not changed. That is, if I open the file and click the page, the name of the document locating at the top of current window is still older name, not changed. So if I stop ibook and reopen it, the name is still.

How can I rename the file name without itunes? It's tedious.

It works very well in older version iBook!