transfer of books from iPad to iPhone and MacBook Pro

Have you synced the iPad to that computer yet ? If not then the steps on this page for syncing to a new computer may be of help : Syncing to a "New" Computer or replacing a "crashed" Hard Drive

Some of the steps on that page have changed slightly (it was written for a previous version of iTunes) :

5, is now File > Devices > Transfer Purchases

6, 'Reset Warnings' at the bottom of the phone's Summary tab in iTunes

7, File > Devices > Back Up

8, File > Devices > Restore from Backup (or Restore Backup button on the Summary tab)

If they are ibooks from the iBookstore then connecting your iPad to your Mac and doing File > Devices > Transfer Purchases should copy them over, and you can then do File > Move Books From iTunes in its iBooks app - or (and if they are still in the store) you might be able to redownload them directly on your Mac via the Purchased link under Quick Links on the right-hand side of the iBookstore in its iBooks app (or on your phone via the Purchased tab in its iBooks app).

For PDFs and/or epubs the Transfer Purchases might also copy them over, but : About iBooks - Apple Support

Add ePub or PDF files that you download from other websites to your iTunes library on your computer from your iOS device

1. Open iTunes.
2. Connect your iOS device.
3. From the menu bar, click File > Devices > Transfer Purchases.

Please note, these ePub and PDF files will only transfer once. After that, you must download them directly from the website to your computer.

So if you had previously copied them to a different computer they might not copy off again. There are some programs listed half-way down this page which might be able to copy them off so that you can add them to iBooks on your Mac : Recover your iTunes library from your iPod or iOS device

You can then sync them to your phone (if they are compatible, some ibooks can only be read on iPads and Mac computers).