How to get back copy of ebook pdf format from ibook?

[blueeye]

Hi , i have a problem is how to get back a copy of the ebook ( pdf format ) from ipad ibook ?

normally i connect iTunes to my ipad , click the ipad book folder then copy the pdf ebook and paste on it . now i want copy back the ebook files , i can't find the copy function in here !

is it need sync to iTunes first then copy from iTunes book folder ?

anyone can help ? Thanks ~~~~~