Can iBooks be synced from an iPad to a new computer to save my documents?
I would evaluate a program like PhoneView to retrieve the contents you like before setting up an iTunes or iCloud backup solution so you don't end up in this spot going forward. There are probably a hundred apps to load files from iOS to a computer, so you can search for one that matches your needs pretty easily. DiskAid also seems to be mentioned regularly even though my favorite is PhoneView.

Here are some relevant details to flesh out how this will work:


Software (not app) To Read Underlying iPhone Data
How to transfer a file from iPhone to computer when there is no Internet?
How can I back up my app data?
On iPad&#39;s iBooks, is there a way to sync and download all ebooks purchased else where?


I have also heard many people express happiness at iExplorer for doing the same sort of recovery / transfer of files from an iOS device. Perhaps it will do a better job with your device since you remarked that several of the suggested apps didn't work for you in the comments.